Editing One-hit KO

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{{incomplete|Needs some more info from Ultimate}}
{{disambig2|attacks with enough knockback to KO in one hit|KOs that occur instantly and bypass all knockback|Instant KO}}
:''For the smasher '''OHKO''', see {{Sm|Okoru}}.''
A '''one-hit KO''', commonly abbreviated as '''OHKO''' (also referred to as an ''Instant KO'' in ''Melee''), is an attack in the ''{{b|Super Smash Bros.|series}}'' games with such high base [[knockback]] that it [[KO]]s an opponent at 0%. Such attacks currently exist in every installment of the series. 

==Definition==

In general, a move is considered a one-hit KO if:

*It is capable of KOing [[Mario]] at 0% ''through sheer knockback alone'' from the middle of the respective game's [[Final Destination]].
*It is not a [[meteor smash]] unless the hitboxes are also capable of OHKOing onstage (meteor smashes like [[Beast Ganon]]'s are therefore OHKOs in ''[[Brawl]]'', while [[Luigi]]'s [[down taunt]] is not).
*It deals damage and/or does not cause a KO by forcibly re-positioning the opponent (such as [[push]] effects and dragging [[Final Smash]]es). There are some exceptions, such as [[Jigglypuff]]'s [[Puff Up]] in ''Brawl'' which has both sheer OHKO power and an extreme push effect, and [[Samus]]' [[Zero Laser]] in the same game, which has dragging hits before the final hit.
*It is not extremely situational (such as the first hit of [[Roy]]'s [[Blazer]] against [[Jigglypuff]] on specific [[stage]]s in ''[[Melee]]'', or Jigglypuff's uncommonly high [[shield jump]]).

Another common standard is to compare the move's knockback to the [[smash attack]] of the [[Home-Run Bat]], one of the few moves intended to be the quintessential OHKO by the developers.

Moves with the potential to OHKO are not necessarily guaranteed to do so, and may fail to OHKO under the following circumstances:
*The opponent [[tech]]s, [[DI]]s, utilizes [[momentum cancel]]ling, and/or [[crouch cancel]]s to reduce the knockback or alter the trajectory of the attack.
*The opponent is flung into a [[wall]], which absorbs enough knockback to prevent the OHKO, or successfully executes a [[wall|wall tech]].
*The move's [[sweetspot]] (if any) does not land (particularly evident for [[sword]]-based hitboxes, such as [[Roy]]’s [[Flare Blade]] in every game featuring him or [[Lyn]]' slash in ''Brawl'').
*The move requires more hitboxes to land but some of them fail (for example, [[Lugia]]’s Aeroblast in ''Melee'', which can whiff if the character is hit on the edge and escapes; in ''Brawl'' it deals a single, immensely powerful hit which always OHKOs, but suffers from a smaller hitbox).
*The stage is extremely large (e.g. [[Temple]], [[New Pork City]], and [[75m]]), or the opponent is at the far edge of a stage.
*The move was weakened previously due to [[stale-move negation]].
*Opponents are under an effect that makes them more resilient (such as being [[Super Mushroom|giant]], [[metal]], or in an event that reduces the knockback they sustain), or the player is weakened (such as being [[Poison Mushroom|tiny]] or given a lower [[handicap]]).
*The [[launch rate]] is lower than standard, reducing knockback.
*The opponent's [[gravity]] is affected via [[equipment]].
*The player is under the effect of a [[sticker]] or a [[spirit]] that increases  resistance to [[flinch]]. It is only possible in [[Adventure Mode]]s.

A [[Final Smash]] executed using [[Final Smash Meter]] always loses its OHKO potential, unless specific spirits prevent this.

==List of One-Hit KOs==
This page lists the moves that can OHKO within the rules mentioned above. 

Certain moves and situations are '''not''' considered to meet the definition of one-"''hit''" KO's:

*Moves or hazards that inflict no [[knockback]], for example, being flown off the screen by the [[Landmaster]] or eaten by the [[Summit]]'s [[Fish]] or [[Distant Planet]]'s [[Bulborb]]), as they simply drag opponents into the [[blast line]]s.
*[[Sacrificial KO]]s, [[self-destruct]]s and [[instant KO]]s (such as [[Bowser]]'s [[Flying Slam]] or [[Hero]]'s [[Whack]]), as they do not deal any conventional knockback. 
*Moves that hit an opponent who is close to a blast line (such as [[Pikachu]]'s very powerful [[Thunder]] in ''[[Brawl]]'' or [[Ike]]’s [[Great Aether]] on specific [[stage]]s in the same game), as almost any typical attack ingame will be able to KO opponents at that point.

Some [[stage hazard]]s or [[enemies]] are capable of OHKOing on their respective stages, and will be listed below.

===In ''[[Super Smash Bros.]]''===
Moves that KO at 0% were almost nonexistent in the original ''Smash''. In fact, aside from the Home-Run Bat, only one move in the game is able to OHKO, under uncommon conditions:
====Items====
*A [[smash attack]] with the [[Home-Run Bat]].
*If [[Fox]] uses [[Reflector (Fox)|Reflector]] on a walking [[Bob-omb]], he (as well as any character caught in the blast radius) will be OHKO'd.
*If two Foxes use Reflector on a [[Green Shell]], it will eventually gain OHKO power after 3-4 reflects.

====Bosses====
The following will usually cause an OHKO on Very Hard [[difficulty]] only:
*{{SSB|Master Hand}}’s [[sweetspot]]ted Dual Poke (if both hits connect), Flying Punch, Power Punch and Jetstream.

====Video====
The following video demonstrates the main moves that KO at 0% in ''Smash Bros'':

{{#widget:YouTube|id=OslLkfYGSwU}}

===In ''[[Super Smash Bros. Melee]]''===
Unlike in ''Smash 64'', there are multiple moves that can OHKO in ''Melee'', including [[Character|playable character]]s’ attacks and [[stage hazard]]s.  They still remain relatively rare, however.

====Playable characters' moves====
*{{SSBM|Roy}}'s almost fully charged or fully charged [[Flare Blade]] (sweetspot).
*{{SSBM|Mr. Game & Watch}}'s fully loaded [[Oil Panic]] after [[absorb]]ing three strong projectiles (such as three [[PK Flash]]es).
*Roy's [[Counter]] (sword hitbox) upon countering a hitbox that deals at least ~35% damage (sweetspot).

Contrary to common belief, Roy's [[Blazer]] is not an OHKO, having very high [[fixed knockback]] but not quite enough to qualify under the required conditions. However, in particular situations it could potentially KO very light characters at 0% in small [[stage]]s if its [[sweetspot]] lands, specifically characters not heavier than {{SSBM|Jigglypuff}}.

====Items/Enemies====
*A [[smash attack]] with the [[Home-Run Bat]].
*Touching [[Moltres]].
*Getting caught in [[Lugia]]'s Aeroblast (if most hits connect). Unlike ''Brawl'', Aeroblast requires more hits to KO at 0%, but its hitbox is very large. Touching Lugia’s body can also lead to an OHKO if multiple hits chain (while a single hit KOs {{SSBM|Mario}}) as low as 35%).
*A thrown [[Polar Bear]] (sweetspot).
*A [[Green Shell]] gains OHKO power when reflected 3 or 4 times by two [[Fox]]es using [[Reflector]].

[[Marill]]'s Tackle can [[push]] players past the side [[blast line]], but as it inflicts no conventional knockback it is not considered a one-hit KO.

Contrary to common belief, [[Articuno]]’s Icy Wind is not an OHKO, having very high knockback but not quite enough to qualify under the required conditions (it usually KOs [[Mario]] starting from 12%). However, this attack could potentially KO lighter characters at 0% on [[Final Destination]] if its [[sweetspot]] lands, specifically characters not heavier than {{SSBM|Pikachu}}.

====Stage hazards====
*[[Corneria]]’s laser beams.
*Touching the hull of the flying ship on [[Rainbow Cruise]].
*The fastest cars on [[Big Blue]].
*On [[Flat Zone]], if a falling tool is launched at enough speed (after either being hit by an extremely powerful attack such as a [[Home-Run Bat]] swing, or being launched after receiving enough damage), it will OHKO anyone it slams into.
*[[Banzai Bill]]'s explosion on [[Princess Peach's Castle]] (if all hits connect).

While touching a [[Klaptrap|Blue Klaptrap]] on [[Jungle Japes]] causes a powerful [[meteor smash]] of OHKO power, it is otherwise unable to cause a conventional OHKO by the standards mentioned above. 

====Bosses====
The following will usually cause an OHKO on Very Hard [[difficulty]] only:
*{{SSBM|Master Hand}}’s Finger Drill (if all hits connect), Tri-Poke (if all hits land).
*{{SSBM|Crazy Hand}}’s Fake-Out Slap and Flying Slap.
*Master Hand and Crazy Hand’s Crush (if all hitboxes land), Power Punch, Flying Punch (sweetspot), and Jetstream (sweetspot).
*Combined Master Hand’s and Crazy Hand’s Applause (if all hits connect) and Sandwich Punch.

====Others====

In [[Cruel mode|Cruel Melee]], almost all the attacks of the [[Fighting Wire Frames]] are powered so much that they can easily OHKO every character. These moves include, for example, [[forward smash]] and [[up smash]], but also punches, kicks, and other moves. The same strengthening, if not, even more, will be seen again in ''Brawl''.

====Video====
The following video demonstrates nearly all the moves and hazards that KO at 0% in ''Melee'':

{{#widget:YouTube|id=mb5qAONMjLs}}

===In ''[[Super Smash Bros. Brawl]]''===
''Brawl'' continued the trend of adding several OHKOs into the game, resulting in a huge number of them (especially in [[The Subspace Emissary]]). However, the majority are [[Final Smash]]es, [[item]]s (mainly [[Pokéball]]s), [[stage hazard]]s, [[enemy]] and [[boss]] attacks, with relatively few being standard moves of playable [[character]]s. 
On the higher [[Difficulty|difficulties]] of The Subspace Emissary (but even on the lower ones in some cases), several enemy attacks are invariable OHKOs, as well as many boss attacks. Also, nearly all [[Tabuu]]'s moves are guaranteed OHKOs in every situation, most of them even in [[Boss Battles]] (where the player has only one [[life]] and no [[continue]]s).

Some notes:
*In the Subspace Emissary, the player's [[gravity]] and [[falling speed]] are automatically increased up to 19% from normal ''Brawls'', making KOs slightly less likely. 
**It is also possible to use [[flinch]] resistance [[sticker]]s to severely reduce knockback, although they can't protect from very powerful OHKOs, at least on the higher difficulties (like Winged Tabuu's [[Off Waves]] or Golden Bracket).
*In Boss Battles, boss attacks are normally weaker, having slightly more than one half of their original speed and power (with some notable exceptions). The difference is more evident on the lower difficulties (Easy overall) than on the higher ones (Intense in particular). This is done to partially compensate the fact that the player has only one [[stock]] and no continues, items or stickers.
**However, since the player’s gravity and falling speed have been restored to normality, boss attacks usually have the same [[knockback]] of the previous difficulty in the Subspace Emissary. This results in most of them maintaining OHKO power one difficulty above.
**[[Master Hand]] and [[Crazy Hand]] are an exception, being severely [[nerfed]] in power, speed and HP from the [[Classic Mode]]. None of their attacks can OHKO in this mode (notice that they only appear separately).

====Playable characters' standard moves====
*{{SSBB|Ike}}'s stage 8 [[Eruption]]. The sword's tip can also inflict a [[meteor smash]] of OHKO power, regardless of the stage.
*{{SSBB|Mr. Game & Watch}}'s fully loaded [[Oil Panic]] after [[absorb]]ing three medium power [[projectile]]s (such as three [[PK Flash]]es) or a very strong one.
*The following [[counterattack]]s:
**Ike's Counter (sword and body hitboxes) upon countering a hitbox that deals at least ~35% damage.
**{{SSBB|Marth}}'s Counter (sword and body hitboxes) upon countering a hitbox that deals at least ~40% damage.
**[[Pit]]’s [[Mirror Shield]] upon countering a very strong projectile or a [[B-reverse|reverse]] attack that deals at least ~30% damage (such as [[Captain Falcon]]’s reverse [[Falcon Punch]] or Ike’s reverse stage 6-9 Eruption). Countering these attacks can deal very high sheer knockback but doesn’t inflict any damage. 
*Any sufficiently strong or repeatedly [[Reflector|reflected]] projectile when reflected or countered, such as {{SSBB|Zelda}}'s fully charged [[Phantom Slash]] or [[Din's Fire]], or a [[Green Shell]].

Contrary to common belief, Mr. Game & Watch's [[Judge]] #9 is not an OHKO, having very high knockback but not quite enough to qualify under the required conditions (it usually KOs  {{SSBB|Mario}} starting from 10%). The same applies to Ike's stage 7 Eruption and {{SSBB|Ganondorf}}'s reverse aerial [[Warlock Punch]], which can both KO Mario as low as 8% but don't respect the general definition. However, all these attacks could potentially KO lighter characters at 0% on [[Final Destination]] if their [[sweetspot]] lands, specifically characters not heavier than {{SSBB|Pikachu}}.
Also, if {{SSBB|Kirby}} [[Inhale|inhales]] Ike or Ganondorf, its copied stage 7 Eruption / reverse aerial Warlock Punch is usually slightly more powerful, KOing Mario as low as 5%. It has now enough power to KO several lighter characters at 0% on Final Destination if its sweetspot lands, specifically characters not heavier than Zelda. 

Although it can't be qualified under the required conditions, [[Pikachu]]'s [[Thunder]] can KO most (if not all) characters at 0% on several specific [[stage]]s with a high enough top platform, due to having very high knockback in ''Brawl''. These stages are [[75m]], [[Rumble Falls]],  [[Hanenbow]], [[Pirate Ship]], [[Flat Zone 2]], [[Mario Bros.]], [[Delfino Plaza]]’s square, the elevated part of [[Rainbow Cruise]], the World 1-2 version of [[Mushroomy Kingdom]] and any [[custom stage]] with an high enough platform. However, since it simply hits opponents close to the blast line, [[Thunderspiking]] can never be truly considered a one-hit KO under the general definition. In fact, used on [[Final Destination]] this move can KO the lighter characters only starting from 45%. 

====Final Smashes====
*{{SSBB|Marth}}'s [[Critical Hit]].
*{{SSBB|Jigglypuff}}'s [[Puff Up]] both by [[push]] and simple contact (the hitbox when Jigglypuff shouts and deflates has extremely high base knockback in ''[[Brawl]]'').
*{{SSBB|Lucario}}'s [[Aura Storm]] at high [[Aura]] if most hits connect. 
**If the initial take off lands, the attack OHKOs {{SSBB|Mario}} when Lucario has only taken 95% damage (roughly a 55% Aura). Considering only the beam’s power, it is an OHKO starting from 125% damage for Lucario (roughly a 73% Aura). 
*{{SSBB|Pokémon Trainer}}'s [[Triple Finish]] if most hits connect (always needs the last hit to land for a KO).
*{{SSBB|Pikachu}}’s [[Volt Tackle]] if all hitboxes land (getting caught by the electrical sphere and hit by the final discharge).
*{{SSBB|Ganondorf}}'s [[Beast Ganon]] if most hitboxes land (at least one stomp and charge). If a character paralyzed by Beast Ganon is not hit by the charge afterward, they will be inflicted a [[meteor smash]] of OHKO power.
*{{SSBB|Zelda}}'s [[Light Arrow]] (guaranteed on the first [[target]]). Power decreases by 25% for each target, but its perfectly horizontal knockback can lead to a guaranteed KO for multiple characters with poor [[recovery]].
**{{SSBB|Sheik}}’s Light Arrow (barely in OHKO threshold, easily [[DI]]ed). Power does not decrease hitting more targets.
*{{SSBB|Link}}’s and {{SSBB|Toon Link}}’s [[Triforce Slash]] if both hitboxes land (multiple slashes and final blow). 
*{{SSBB|Samus}}' [[Zero Laser]] if most hits connect.
*{{SSBB|Zero Suit Samus}}' [[Power Suit Samus]] if both hitboxes chain (being sucked by the [[vacuum]] and contact with her body). However, it only works if the character is extremely close to Zero Suit Samus before she starts sparkling.
*{{SSBB|Olimar}}'s [[End of Day]] if all hitboxes land (bury, ascent, and explosion). Offstage opponents hit by the rocket's thrusters will also experience an OHKO via meteor smash.
*{{SSBB|Captain Falcon}}’s [[Blue Falcon]].
*[[Wario-Man]]'s [[Wario Waft]] with enough charge. It OHKOs Mario starting from 1 minute and 20 seconds (roughly a 73% charge).

{{SSBB|Luigi}}’s [[Super Jump Punch]] during [[Negative Zone]] can KO almost all characters at 0% in several situations, but it is not considered a true one-hit KO under the general definition. In fact, while Negative Zone is active, characters’ [[weight]] could be severely reduced, making KOs much more likely. This Final Smash will also inflict damage to the characters: it implies that, when Luigi’s Super Jump Punch lands, characters have already taken more than 0% damage.

Despite lacking enough knockback to be qualified under the required conditions, {{SSBB|Ike}}'s [[Great Aether]] can KO most (if not all) characters at 0% on several specific [[stage]]s, if all hitboxes land (blade swing, multiple slashes or kicks and final blowing explosion). These stages are [[75m]], [[Rumble Falls]], [[Hanenbow]], [[Flat Zone 2]], [[Pirate Ship]], [[Mario Bros.]], [[Onett]], [[Summit]], [[Spear Pillar]], [[Luigi Mansion]], [[Skyworld]], [[The Ruins]], [[Delfino Plaza]]'s square, the elevated part of [[Rainbow Cruise]], the World 1-2 version of [[Mushroomy Kingdom]] and any [[custom stage]] with an high enough platform. However, despite being a guaranteed KO under these conditions, it doesn't fit the general definition: in fact, the opponent is simply brought up to the top platform, very close to the stage [[Blast line|boundary]], before being KOed. Used on [[Final Destination]], this move can KO the lighter characters only starting from 20%. 

====Items====
*The [[Dragoon]].
*A [[smash attack]] with the [[Home-Run Bat]].
*Touching [[Moltres]].
*[[Lugia]]'s Aeroblast. Unlike ''Melee'', a single hit will always OHKO the characters (without trapping them in most cases), but the attack suffers from a smaller hitbox. Touching Lugia’s body can also lead to an OHKO if multiple hits chain (while a single hit KOs {{SSBB|Mario}}) as low as 30%).
*[[Articuno]]’s Sheer Cold.
*[[Suicune]]'s Aurora Beam. The beam will not [[freeze]] at 0%, but still deals more than enough knockback to OHKO regardless.
*[[Ho-oh]]’s Sacred Fire if most hits connect (always needs the last hit to land for a KO). Midair opponents are also OHKOed by a very powerful [[meteor smash]].
*[[Deoxys]]'s Hyper Beam (or touching its body), both the initial hit and the following multi-hitting laser.
*A thrown [[Bonsly]] (sweetspot).
*[[Electrode]]'s Explosion or when smash thrown. If an Electrode fails to burst, it can still be picked up and smash thrown with guaranteed OHKO power.
*[[Weavile]]'s False Swipe if both hitboxes land (multiple slashes with [[stun]] effect and either the final blowing slash or an uppercut on airborne characters).
*[[Gardevoir]]'s Reflect upon reflecting a strong enough [[projectile]] (such as a [[Bob-omb]] or {{SSBB|Zelda}}'s [[Din's Fire]]; it cannot reflect a [[Hothead]]). It is the most powerful [[Reflector]], dealing double the original projectile's damage and knockback.
*[[Wobbuffet]]’s [[Counter]] (automatically used at every hit; body hitbox) when countering an OHKO attack or a hitbox that deals at least ~25% damage.
*[[Metagross]]' Earthquake if all hitboxes land (bury, stomps and upward smash). It also has a powerful meteor smash capable to OHKO nearby midair characters.
*[[Latios and Latias]]’ Steel Wing if all hits chain (needs to trap characters in the [[vacuum]]).
*[[Snorlax]]’s Body Slam if both hits chain (initial jump or contact with its body and being hit by the Body Slam afterwards).
*[[Dr. Wright]]’s highest skyscraper.
*[[Lyn]]’s slash (sweetspot). 
*[[Knuckle Joe]]'s attacks if both hitboxes land (Vulcan Jab and either Rising Break or Smash Punch).
*[[Waluigi]]'s Racket Smash, sweetspotted, if all hitboxes land (bury, multiple stomps and finishing kick or blow). It can also OHKO characters by meteor smash.
*[[Little Mac]]’s uppercut (sweetspot).
*At least two [[Blast Box]]es or four [[Smart Bomb]]s, [[Gooey Bomb]]s or [[Bob-omb]]s exploding at the same time.
*If {{SSBB|Wario}} runs over a buried [[Pitfall]] while riding on his [[Wario Bike]], he will be sent flying at OHKO power. A thrown Pitfall can also meteor smash midair opponents with OHKO power.
*When a [[Hothead]] reaches its full power for the last seconds before fading, or after taking enough [[damage]], any contact will be an OHKO (touching the [[spark]]s is even more powerful).
**If an uncharged Hothead is hit by an [[electric]] or [[flame]]-based hitbox that deals at least 30% damage (such as [[Ike]]’s stage 6-9 [[Eruption]]), it will OHKO when smash thrown or launched. Any contact while traversing the stage at this strength (or with the sparks it emits) will also OHKO.
*If a [[Soccer Ball]] is launched at enough speed (after either being hit by an extremely powerful attack such as [[forward smash]] or a Home Run bat swing, or simply being launched after receiving enough damage), it will OHKO anyone it slams into.
*A [[Green Shell]] gains OHKO power when countered 3 or 4 times by a [[Reflector]] (for example [[Fox]]'s or [[Pit]]’s). This also applies to Green Shells and [[Red Shell]]s obtained by defeating a [[Koopa Troopa]] or [[Koopa Paratroopa]] in [[The Subspace Emissary]] and to [[Shellcreeper]]s in [[Mario Bros.]] stage. Red Koopa Shells and Shellcreepers are usually much more powerful when reflected.

[[Isaac]], [[Devil]], [[Kyogre]]'s Hydro Pump and [[Piplup]]'s Surf can [[push]] players into the side [[blast line]], but as they inflict no conventional knockback they are not considered one-hit KOs.

====Stage hazards====
*The [[Ultimate Chimera]]'s bite on [[New Pork City]].
**If the the bite lands on the mouth’s edge, it deals the same, immense knockback of [[Marth]]’s [[Critical Hit]]. If the bite traps the character inside the mouth (or the Ultimate Chimera turns around to inflict a reverse bite), both knockback and damage are even higher, rivalling [[Tabuu]]’s [[Off Waves]] on the higher [[Difficulty|difficulties]].
*[[Dialga]]'s Roar of Time and Overheat (or touching its body), [[Palkia]]'s Spacial Rend and [[Cresselia]]'s Psycho Cut (at full power before fading) on [[Spear Pillar]].
*The fastest forms of [[Sidestepper]]s (Red) and [[Shellcreeper]]s (both Blue and Pink) on [[Mario Bros.]], or every other version of them when smash thrown or launched. Touching the fastest red or green [[Flame]]s is also an OHKO.
*The fastest cars on [[Big Blue]].
*[[Corneria]]'s laser beams.
*The energy blast shot by [[Halberd]]’s Combo Cannon if all hits connect. 
*Touching the hull of the [[Pirate Ship]].
**If a character is fired by the catapult and hit by a strong attack at the same time (such as {{SSBB|Pikachu}}’s [[Thunder]], very powerful in this game), it could potentially be OHKOed. However, this only happens if the two hits chain in a few [[frame]]s, since the attacks combine to dramatically boost their knockback.
*Touching the hull of the flying ship on [[Rainbow Cruise]].
*On [[Flat Zone 2]], if a falling tool is launched at enough speed (after either being hit by an extremely powerful attack such as a [[Home-Run Bat]] swing, or being launched after receiving enough damage), it will OHKO anyone it slams into. 
**Other hazards are also capable of OHKOs on this stage, such as Lion Tamers.
*Being hit by the falling [[spear]]s on [[PictoChat]].
*[[Norfair]]'s giant magma wave if all hits connect.
*The bomb on [[Bridge of Eldin]].
*The first and fourth spikes on [[Rumble Falls]] (can easily be teched).

While touching a [[Klaptrap]] on [[Jungle Japes]] causes a powerful [[meteor smash]] of OHKO power, it is otherwise unable to cause a conventional OHKO by the standards mentioned above. 

====The [[Subspace Army]] (enemies and opponents)====
The following will usually cause an OHKO on Intense [[difficulty]] only:
*[[Armight]]'s double sword throw.
*[[Boom Primid]]'s boomerang.
*Touching a [[Bullet Bill]].
*[[Bytan]]'s full power charge.
*[[Cymul]]'s rotating blades (if all hits connect; always needs the last slash to land for a KO).
*[[Feyesh]]'s sparkling slash.
*[[Gamyga]]'s laser beam (both complete and incomplete form).
*Touching [[Glice]], [[Glire]] and [[Glunder]].
*[[Hammer Bro]]’s headbutt.
*Multiple [[Mite]]’s aerial attack (together, if all hits chain).
*Every [[Nagagog]]'s martial attack.
*A wrench or a stone thrown by [[Poppant]].
*The fiery punch of five [[Primid]] variants (all except Boom Primid and [[Scope Primid]], which can’t punch).
*[[Puppit]]'s slash and laser beam.
*[[Roturret]]'s projectiles.
*[[Spaak]]'s thunderbolt and [[vacuum]] (white form). 
*Several attacks of [[Shadow Bug|Shadow Clones]], [[False character|Subspace Copies]] and [[Boss|opponents]], such as forward smash and [[up smash]], but also punches, kicks, and many others. A similar type of strengthening is seen in [[Cruel mode|Cruel Brawl]].

The following will cause an OHKO on both Very Hard and Intense difficulties:
*[[Armank]]'s electrical pulse.
*[[Auroros]]'s sky-diving attack.
*[[Autolance]]'s giant lance projectile (both armored and armorless form).
*[[Big Goomba]]' charge.
*Touching a [[Bombed]] or contact with its thrown head.
*[[Greap]]'s scythe swing.
*[[Roader]]'s charge.
*The [[forward smash]] of all four [[R.O.B.]] variants.
*Every [[Shaydas]]' double blade slash.
*[[Shellpod]]' charge (both armored and armorless form).
*[[Spaak]]'s thunderbolt and [[vacuum]] (dark form). 

The following will cause an OHKO on Hard or higher difficulties:
*[[Armank]]'s ramming and sweeping attacks.
*[[Buckot]]'s fire shards (if most hits connect).
*[[Bytan|Giant Bytan]]'s full power charge (at low health).
*[[Greap]]'s ax chop.
*Every [[Shaydas]]' triple blade slash (only used at low health).
*[[Ticken]]'s charge.
*[[Towtow]]'s charge.

The following will cause an OHKO on Normal or higher difficulties:
*[[Armight]]'s double blade slash.
*[[Autolance]]'s piercing forward lunge (both armored and armorless form).
*[[Big Primid]]'s [[forward smash]], body slam, fiery punch and kick.
*[[Bytan|Giant Bytan]]'s full power charge.
*Every [[Nagagog]]'s martial attack (the last form, at low health).
*[[Shaydas]]' blade cross.

The following will cause an OHKO on every difficulty:
*[[Armight]]'s [[combo]] attack if most hitboxes land (at least one double slash and final blow; always needs the last hit to land for a KO).
*[[Autolance]]'s combo attack if both hitboxes land (thrust and skyward swipe; both armored and armorless form).
*[[Floow]]'s mind attack (if most hits connect or at full health).
**Multiple Floows' combined scream (together, only used by two or more Floows at full health).
*A [[Koopa Troopa]] or [[Koopa Paratroopa]]'s Shell when [[Reflector|reflected]].
*[[Nagagog]]'s body slam at very low health (only used by the last form).
*[[Scope Primid]]'s most powerful projectile.
*[[Shaydas]]' combo attack if most hits connect.
*Nearly all the direct attacks of [[Shadow Bug|Giant Shadow Clones]] and [[False character|Giant Subspace Copies]], such as [[Diddy Kong|Giant Shadow Diddy Kong]].

Touching a [[Trowlon]] on every difficulty is not an OHKO in conventional terms, since it simply carries the player past the top [[blast line]] for a guaranteed KO. The only way to survive is by jumping off. 
The same applies to [[Borboras]]' very powerful [[wind]], that [[push]]es the player offscreen with power drastically increasing with the difficulty, and to [[Bucculus]]' kiss (although this one is very easy to avoid).

Many other enemies and several opponents are also capable of OHKOs.

====The [[Subspace Army]] (hazards and traps)====

The following will cause an OHKO on Hard or higher [[Difficulty|difficulties]]:
*Touching [[Jyk]] (all the three variants).

The following will cause an OHKO on Normal or higher difficulties:
*Touching the [[Porky Statue]].

The following will cause an OHKO on every difficulty:
*Touching the hull of [[Battleship Halberd Bridge|The Halberd]].
*Touching very powerful [[flame]]s or bright [[laser]] spheres (such as in [[The Subspace Bomb Factory (Part II)|the Subspace Bomb Factory]]).
*The [[Porky Statue]]’s crushing jump and falling attack.
*Touching a [[Quark Mine]].

Notice that the [[Porky Statue]], [[Jyk]]s and [[Quark Mine]]s are sometimes considered [[Enemy|enemies]], since they move and chase the player.

Other hazards are also capable of OHKOs, while others can inflict an [[Instant KO]].

====The [[Subspace Army]] (bosses)====
The following will usually cause an OHKO on Intense [[difficulty]] only:
*[[Petey Piranha]]'s Left or Right Cage Smash boosted by Roar (it only happens twice per battle when each cage reaches 1/3 [[HP]]; always noticed due to the red aura). 
*Several of [[Rayquaza]]'s moves at low health (25% or less):
**Sweetspotted Dig, Ground Burst and Air Dash & Extremespeed. 
*Several of [[Rayquaza]]'s moves at very low health (5% or less):
**Iron Tail boosted by Roar (sweetspot; Roar is sometimes used to [[push]] the player away and slightly increase the knockback of certain moves).
**Horizontal Electric Ball and Diagonal Electric Ball.
*[[Porky Minch]]'s Jump (sweetspot) and Energy Laser (both variants). 
*[[Ridley]]'s Flying Stomp (sweetspot), Loop-de-Loop (if most hits connect), Tail Swoop (if most hits connect at very low health; always needs the last hit to land for a KO) and Slamming Rush. 
*Several of [[Duon]]'s moves:
**Triple Slash (if most hits connect; always needs the last hit to land for a KO) and Blue Bolts or Vertical Pink Shots (contact with the bright blue / pearl sphere only, not the beams - which KO at 30%).
**Homing Missiles if all the four chasing [[projectile]]s explode at the same time. 
*[[Galleom]]'s Side Crush (sweetspot) and Uppercut (sweetspot).
*[[Meta Ridley]]'s Tail Swoop if most hits connect (always needs the last hit to land for a KO).
*[[Tabuu]]'s Diving Slash (sweetspot) and Ghost Projection (clones and Tabuu's body hitbox).

The following will cause an OHKO on both Very Hard and Intense difficulties:
*[[Rayquaza]]'s Lightning Strike (only used at low health; it deals massive [[fixed knockback]] that increases with difficulty) and Blast.
*[[Porky Minch]]'s Stabbing Flurry (if most hits connect; always needs the last hit to land for a KO).
*Touching the Porky Bots sent out by Porky Minch.
*[[Ridley]]'s Background Ram.
*[[Duon]]'s Vacuum Spin (if most hits connect or via [[meteor smash]]) and Charge.
*[[Galleom]]'s Shockwave (first punch only), Tank Rush (only used by Tank Galleom at medium to high health) and Jump.
*[[Tabuu]]’s Explosive Teleport and Shuriken Boomerang (second swing).

The following will cause an OHKO on Hard or higher difficulties:
*[[Porky Minch]]'s Dash.
*[[Duon]]'s Sword Blast (the slash itself, not the shockwave - which KOs below 20% on Intense), Head Sword Chop and Jump Crash.
*[[Meta Ridley]]’s Mega Fire Ball.
*[[Galleom]]'s Tank Rush & Slam (both hitboxes; the falling attack is quite stronger and only used by Tank Galleom at low health), Tornado Spin (if most hits connect) and Falling Body Slam.
*[[Tabuu]]'s Shuriken Boomerang (first swing), Shark Blade (blade and Tabuu’s body hitbox), Bullet Rain (second hitbox: the huge energy sphere), Chain of Light (on a single [[target]]) and Pinpoint Explosion.

The following will cause an OHKO on Normal or higher difficulties:
*Several of [[Tabuu]]'s moves:
**Dragon Laser. 
**Chain of Light on two [[target]]s. Tabuu will attempt to smash the [[Player|players]] together with the Chain, nearly always resulting in a double OHKO.
**Golden Bracket (on a single [[target]]) and Electrical Shield (sparkles and Tabuu’s body hitbox). Due to perfectly horizontal knockback, these attacks will also cause a guaranteed KO for poor [[recovery]] characters even on Easy difficulty.

The following will cause an OHKO on every difficulty:
*[[Porky Minch]]'s Lightning if most hits connect or Porky has low health (25% or less). 
*[[Meta Ridley]]’s Falcon Flyer Smash and Falcon Flyer Stamp. These attacks will also drag the player past the bottom [[blast line]] for a guaranteed KO. In any case, the only way to survive is by jumping. 
**However, contact with Meta Ridley while it's rising after Falcon Flyer Smash will send the player past the blast line for a guaranteed KO, forcing the player to pay attention before landing.
*Several of [[Tabuu]]'s moves:
**Rapid Chop if most hits connect (always needs the last slash to land for a KO). 
**Golden Bracket on two [[target]]s. Tabuu will attempt to smash the [[Player|players]] together, always resulting in a double OHKO. The same happens if both players are trapped in the cage.
**[[Off Waves]] (waves and Winged Tabuu’s body hitbox). 
***In the [[Subspace Emissary]] (but not in [[Boss Battles]]), Off Waves are the only move to be [[nerfed]] in [[Multiplayer|co-op mode]] (in both speed and power), regaining their guaranteed OHKO power on Normal difficulty. This may be to compensate the fact that they cover the entire screen and are Tabuu's strongest move. However, their [[sweetspot]] or contact with Winged Tabuu will still OHKO on Easy difficulty.
*These small hitboxes always deal a guaranteed KO:
**Touching the sparkling spheres of Porky Minch's Lightning and Energy Beam, or jumping on Porky during these moves.
**Standing on [[Duon]] while Jump Crash is performed.
**Touching Tabuu's hand when he shoots the huge energy sphere during Bullet Rain attack (always noticed due to the red flash).

[[Meta Ridley]]'s Falcon Flyer Pull on every difficulty is not an OHKO in conventional terms, since it simply drags the player past the bottom [[blast line]] for a guaranteed KO. The only way to survive is by jumping.
[[Ridley]]’s Blasting Roar, [[Porky Minch]]'s Dash and [[Galleom]]'s Shockwave can also carry the player past the side blast lines, but only under certain conditions and can be easily avoided.

[[Tabuu]]'s Bullet Rain is always a KO on every difficulty if the player is hit both by the first (high-damaging bullets) and the second hitbox (explosive sphere). However, since the two hitboxes are separated by a brief interval when the player is free to move, this move can't be considered an OHKO on all difficulties. The same applies to Tabuu's Electrical Shield: on lower difficulties only, when the players touch the spark rings (but not Tabuu's body) they will simply flinch, although they can be sucked in repeatedly by a very powerful [[vacuum]] effect before being KOed.

Other boss attacks are also capable of OHKOs.

====Classic Mode (bosses)====
The following will usually cause an OHKO on Intense [[difficulty]] only:
*{{SSBB|Master Hand}}’s Tri-Poke (if all hits connect), Crush (if most hitboxes land) and Vertical Throw.
*{{SSBB|Crazy Hand}}’s Squeeze (if most hitboxes land), Flying Slap and Fake-Out Slap.
*Master Hand's and Crazy Hand’s Power Punch, Flying Punch and Jetstream. 
*Combined Master Hand and Crazy Hand's Sandwich Punch (guaranteed).

The following will cause an OHKO on both Very Hard and Intense difficulties:
*{{SSBB|Master Hand}}'s and {{SSBB|Crazy Hand}}'s Finger Drill if most hits connect. 
*Combined Master Hand’s and Crazy Hand’s Applause (if most hits connect), Sandwich Punch (sweetspot) and Crush Punch.

====Boss Battles (bosses)====
The following will usually cause an OHKO on Intense [[difficulty]] only:
*[[Rayquaza]]'s Lightning Strike (only used at low health; it deals massive [[fixed knockback]] that increases with difficulty) and Blast.
*[[Porky Minch]]'s Stabbing Flurry (if most hits connect; always needs the last hit to land for a KO).
*[[Ridley]]'s Background Ram.
*[[Duon]]'s Vacuum Spin (if most hits connect or via [[meteor smash]]) and Charge.
*[[Galleom]]'s Shockwave (first punch only), Tank Rush (only used by Tank Galleom at medium to high health) and Jump.
*[[Tabuu]]’s Explosive Teleport and Shuriken Boomerang (second swing).

The following will cause an OHKO on Very Hard or higher difficulties:
*Several of [[Porky Minch]]'s moves: 
**Lightning if most hits connect or Porky has low health (25% or less).
**Dash.
*[[Duon]]'s Sword Blast (the slash itself, not the shockwave - which KOs below 40% on Intense), Head Sword Chop and Jump Crash.
*[[Meta Ridley]]’s Mega Fire Ball.
*[[Galleom]]'s Tank Rush & Slam (both hitboxes; the falling attack is quite stronger and only used by Tank Galleom at low health), Tornado Spin (if most hits connect) and Falling Body Slam.
*[[Tabuu]]'s Shuriken Boomerang (first swing), Shark Blade (blade and Tabuu’s body hitbox), Bullet Rain (second hitbox: the huge energy sphere), Chain of Light (on a single [[target]]) and Pinpoint Explosion.

The following will cause an OHKO on Hard or higher difficulties:
*Several of [[Tabuu]]'s moves:
**Dragon Laser. 
**Chain of Light on two [[target]]s. Tabuu will attempt to smash the [[Player|players]] together with the Chain, resulting in a double OHKO.
**Golden Bracket (on a single target) and Electrical Shield (sparkles and Tabuu’s body hitbox). Due to perfectly horizontal knockback, these attacks will also cause a guaranteed KO for poor [[recovery]] characters even on Easy difficulty.

The following will cause an OHKO on Normal or higher difficulties:
*Several of [[Tabuu]]'s moves:
**Golden Bracket on two [[target]]s. Tabuu will attempt to smash the [[Player|players]] together, nearly always resulting in a double OHKO. The same happens if both players are trapped in the cage.
**[[Off Waves]] (guaranteed; waves and Winged Tabuu’s body hitbox).

The following will cause an OHKO on every difficulty:
*[[Meta Ridley]]’s Falcon Flyer Smash and Falcon Flyer Stamp. These attacks will also drag the player past the bottom [[blast line]] for a guaranteed KO. In any case, the only way to survive is by jumping.
**However, contact with Meta Ridley while it's rising after Falcon Flyer Smash will send the player past the blast line for a guaranteed KO, forcing the player to pay attention before landing.
*Several of [[Tabuu]]'s moves:
**Rapid Chop if most hits connect (always needs the last slash to land for a KO). 
**[[Off Waves]] (sweetspot or contact with Winged Tabuu). It is nearly always guaranteed on lighter characters, specifically characters not heavier than {{SSBB|Zelda}}. 
***Even the [[sourspot]] always OHKOs on Normal difficulty and above.
*These small hitboxes always deal a guaranteed KO:
**Touching the sparkling spheres of Porky Minch's Lightning and Energy Beam, or jumping on Porky during these moves.
**Standing on [[Duon]] while Jump Crash is performed.
**Touching Tabuu's hand when he shoots the huge energy sphere during Bullet Rain attack (always noticed due to the red flash).

[[Meta Ridley]]'s Falcon Flyer Pull on every difficulty is not an OHKO in conventional terms, since it simply drags the player past the bottom [[blast line]] for a guaranteed KO. The only way to survive is by jumping.
[[Ridley]]’s Blasting Roar, [[Porky Minch]]'s Dash and [[Galleom]]'s Shockwave can also carry the player past the side blast lines, but only under certain conditions and can be easily avoided.

[[Tabuu]]'s Bullet Rain is always a KO on every difficulty if the player is hit both by the first (high-damaging bullets) and the second hitbox (explosive sphere). However, since the two hitboxes are separated by a brief interval when the player is free to move, this move can't be considered an OHKO on all difficulties. The same applies to Tabuu's Electrical Shield: on lower difficulties only, when the players touch the spark rings (but not Tabuu's body) they will simply flinch, although they can be sucked in repeatedly by a very powerful [[vacuum]] effect before being KOed.

Other boss attacks are also capable of OHKOs.

====Others====
*In [[The Subspace Emissary]], when [[Auroros]]’s sky-diving attack fails to hit the player, its beak gets stuck in the ground. Players can pull it out and use it as a thrown [[item]], like a javelin or a [[spear]]. A thrown Auroros deals very high knockback and damage, enough to defeat several enemies at 0%. Apparently its power is comparable to that of many one-hit KO moves, but it can never be truly tested outside the Subspace Emissary. Furthermore, on higher [[Difficulty|difficulties]] an Auroros can’t be thrown far before being destroyed, and on Intense it can never hit enemies.
*The [[Sandbag]] used  in the [[Stadium]] for [[Home-Run Contest]] gains OHKO power when smashed with a very powerful attack (such as [[Ganondorf]]'s aerial reverse [[Warlock Punch]]). However, this [[item]] can never be used outside the Stadium, except in [[Training]].
*In [[Cruel mode|Cruel Brawl]], almost all the attacks of the [[Fighting Alloy Team]] are powered so much that they can easily OHKO every character. These moves include, for example, [[forward smash]] and [[up smash]], but also punches, kicks and a very high number of moves. Each of the Alloys has also more powerful specific attacks, such as kicks for the Blue Alloy or punches for the Red Alloy, which are both a guaranteed OHKO from the center of the stage even for [[Bowser]]. A similar type of strengthening (or slightly lower) was seen in ''Melee''. Also, the [[Shadow Bug|Shadow Clones]], [[False character|Subspace Copies]] and [[Boss|opponents]] battled in the Subspace Emissary are powered up this way on the higher [[Difficulty|difficulties]] only.

====Video====
The following video demonstrates some moves and hazards that KO at 0% in ''Brawl'':

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This video shows some other OHKOs, including more [[boss]] attacks.

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===In ''[[Super Smash Bros. 4]]''===
Like ''Brawl'', ''SSB4'' continues to add OHKOs to the game, though mostly playable [[character]]s’ moves. On the other hand, many [[Final Smash]]es and [[item]]s that were able to one-hit KO before have been severely [[nerfed]] in this game. Also, [[Bayonetta]]'s [[Infernal Climax]] becomes the first playable character's move capable of an [[Instant KO]].  

====Playable characters' standard moves====
*{{SSB4|Roy}}'s almost fully charged and fully charged [[Flare Blade]] (sweetspot).
*{{SSB4|Ike}}’s [[Quick Draw|Unyielding Blade]] (sweetspot).
*{{SSB4|Mr. Game & Watch}}'s fully loaded [[Oil Panic]] after [[absorb]]ing three medium power projectiles or a very strong one.
*{{SSB4|Villager}}'s [[Pocket]] after it has absorbed a particularly strong projectile, most notably [[Timber]]. Powerful projectiles released by Pocket that can still be reflected will also OHKO, such as {{SSB4|Zelda}}'s fully charged [[Phantom Slash]].
**Many other [[reflector]]s also share this behaviour, especially {{SSB4|Ness}}'s bat.
*The following [[counterattack]]s:
**Ike's [[Smash Counter]] and {{SSB4|Shulk}}'s [[Power Vision]] custom moves upon countering a hitbox that deals 30% damage or more.
**{{SSB4|Corrin}}'s [[Counter Surge]], Ike and Roy's [[Counter]], and Shulk's [[Vision]] upon countering a hitbox that deals 35% damage or more. These counters technically have varying degrees of knockback, but they nevertheless achieve a KO at 0% without DI.
**{{SSB4|Mii Swordfighter}}'s [[Blade Counter]] upon countering a hitbox that deals 37% damage or more.
**{{SSB4|Lucina}} and {{SSB4|Marth}}'s Counter, {{SSB4|Little Mac}}'s [[Slip Counter]], and {{SSB4|Palutena}}'s {{B|Counter|Palutena}} upon dealing the 50% damage cap with their counters (this requires countering a hitbox that deals at least ~38.5% damage for Little Mac and Palutena, and at least 40% damage with Lucina and Marth).

Contrary to its name and intention, Little Mac's [[KO Uppercut]] does not KO until above about 30% damage. At 0% it falls short of the necessary amount of knockback, KOing a character as light as {{SSB4|Jigglypuff}} at 12%.
Also, {{SSB4|Ganondorf}}'s reverse aerial [[Warlock Punch]] is the most powerful non-OHKO attack, KOing {{SSB4|Mario}} from the center of [[Final Destination]] as low as 1% on its [[sweetspot]]. It means this move can easily KO all the characters lighter than Mario itself at 0% when sweetspotted. With [[Rage]], it eventually gains OHKO power.   

====Playable characters' moves (with Rage applied)====
While the following moves do not guarantee OHKO power under normal circumstances, with [[Rage]] they can perform an OHKO:
*{{SSB4|Lucario}}'s fully charged [[forward smash]], [[Aura]] and Rage stack.
*{{SSB4|Ganondorf}}'s reverse and / or aerial [[Warlock Punch]]. 
*{{SSB4|Kirby}}'s [[Giant Hammer]].

====Final Smashes====
*{{SSB4|Marth}} and {{SSB4|Lucina}}'s [[Critical Hit]].
*Some of [[Giga Mac]]'s attacks when fully charged and [[Sweetspot|sweetspotted]]:
**[[Straight Lunge]], [[up smash]] and [[forward smash]] (when angled up or horizontally).
*{{SSB4|Shulk}}'s [[Chain Attack]] when boosted with the [[Monado Arts#Customization|Hyper Smash Monado Art]] (Extremely frame-precise, as the final hit must land before the Art expires, as shown in [https://youtu.be/F89Sm_jA38g?t=111 this demonstration video]).
*{{SSB4|Captain Falcon}}'s [[Blue Falcon]] (barely in OHKO threshold, easily [[DI]]ed by holding towards the stage).
*[[Wario-Man]]'s fully charged [[Wario Waft]].

====Items====
*The [[Dragoon]].
*A smash attack with the [[Home-Run Bat]].
*The [[Daybreak]] if all hits connect.
*[[Electrode]]'s Explosion after being smash thrown.
*If a [[Hothead]] is powered up significantly by a [[flame]]-based hitbox (30% total or higher), it will gain OHKO power when smash thrown or emitting [[spark]]s. Unlike ''Brawl'', Hotheads don't reach OHKO power automatically for the last seconds or after taking non-fire damage.
*If a [[Soccer Ball]] is launched at enough speed (after either being hit by an extremely powerful attack such as a Home-Run Bat, or being launched after receiving enough damage), it will OHKO anyone it slams into on it’s sweetspot.
*[[Smash attack]]s boosted by the [[Black Knight]] item from [[Smash Tour]] are occasionally turned into OHKOs (random).

[[Beetle]], [[Boss Galaga]], [[Kyogre]]'s Hydro Pump and [[Oshawott]]'s Surf can [[push]] the players past the [[blast line]]s, but as they inflict no conventional knockback they are not considered one-hit KOs. The first two can also be easily escaped by button mashing at 0%.

====Stage hazards====
*Touching the hull of the boat on [[Wuhu Island]].
*Touching the hull of the [[Pirate Ship]].

While touching a [[Klaptrap]] on [[Jungle Japes]] causes a powerful [[meteor smash]] of OHKO power, it is otherwise unable to cause a conventional OHKO by the standards mentioned above. 

====Other====
While it isn't accessible in regular battles, the [[Target Blast bomb|bomb]] used in the [[Target Blast]] stage apparently has more than enough power to OHKO under normal conditions.

====Bosses====
The following will usually cause an OHKO on 8.0 or higher [[Difficulty|difficulties]]:
*These [[Master Core]]'s attacks:
**Blast Waves if the player does not defeat it in time (about 45 seconds).
*The final explosion after unleashing the last Blast Wave (sweetspot). However, it can never truly defeat the players as they have already won by the time the hitbox lands.

{{#widget:YouTube|id=vfWVGiCxTaI}}

====Video====

The following video demonstrates all the moves and attacks that KO at 0% in “Smash 4”:
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===In ''[[Super Smash Bros. Ultimate]]''===
Like ''SSB4'', ''Ultimate'' continues to add OHKOs to the game, though still focusing on playable [[character]]s’ moves (while [[Final Smash]]es and [[item]]s have been slightly [[nerfed]] again from the previous game). Several characters also gain the ability to [[instant KO]] through Final Smashes or special moves; these do not count as OHKOs and belong in its respective page.
====Playable characters' moves====
*{{SSBU|Roy}} and {{SSBU|Chrom}}'s almost fully charged or fully charged [[Flare Blade]] (sweetspot).
*{{SSBU|Hero}}'s fully charged [[forward smash]] with [[Command Selection|Oomph]] or [[Command Selection|Psyche Up]] active (if the sweetspot lands as a critical hit).
*{{SSBU|Kirby}}'s reversed aerial [[Warlock Punch]] (after [[inhaling]] {{SSBU|Ganondorf}}).
*The following [[counterattack]]s:
**Roy and Chrom's [[Counter]], {{SSBU|Joker}}'s [[Rebel's Guard|Tetrakarn]] with [[Arsene]], {{SSBU|Shulk}}'s [[Vision]] with [[Monado Arts|Smash Art]], and {{SSBU|Mii Brawler}}'s [[Counter Throw]] countering a hitbox that deals around 35% damage or more.
**{{SSBU|Corrin}}'s [[Counter Surge]] and {{SSBU|Ike}}'s [[Counter]] countering a hitbox dealing around 40% damage or more.
**{{SSBU|Marth}} and {{SSBU|Lucina}}'s [[Counter]] countering a hitbox dealing around 43% damage or more.
**Any sufficiently strong or repeatedly [[Reflector|reflected]] projectile when reflected.
*Any throwable item under extreme conditions which cause them to move at a very high speed. An example is {{SSBU|R.O.B.}}'s fully-charged [[Gyro]].

====Playable characters' moves (with Rage applied)====
*{{SSBU|Hero}}'s [[Command Selection|Hatchet Man]] with [[Command Selection|Psyche Up and Oomph]] active (Hatchet Man with Psyche Up can OHKO).
*{{SSBU|Mr. Game & Watch}}'s [[Oil Panic]] after [[absorb]]ing a very strong projectile (like {{SSBU|Hero}}'s [[Frizz|Kafrizz]]).
*[[Mr. Game & Watch]]’s [[Judge]] #9.
*{{SSBU|Ganondorf}}'s reversed aerial [[Warlock Punch]].

====Final Smashes====
*{{SSBU|Marth}} and {{SSBU|Lucina}}'s [[Critical Hit]].
*{{SSBU|Lucario}}'s [[Aura Storm]] at max [[Aura]] if all hits connect.
*{{SSBU|Olimar}}'s [[End of Day]] if it hits a fighter that cannot be [[buried]]. End of Day's bury hitbox deals 633.15 units of knockback, more than enough to KO any character on ''Ultimate'''s [[Training (stage)|Training Mode Stage]].

Final Smashes executed using [[Final Smash Meter]] always lose their OHKO power, with Critical Hit KOing [[Mario]] at 20%.

====Items====
*The [[Dragoon]].
*A smash attack with the [[Home-Run Bat]].
*[[Electrode]]'s Explosion when smash thrown.
*A [[Hothead]] when brought from no charge to significant overcharge by a single [[Flame|fire]] attack that deals over 30% damage. Hothead's damage output depends on the average damage output of the moves used to bring it to full charge, and thus gains OHKO power when overcharged by an extremely powerful fire move. If the Hothead hits opponents while [[spark]]ing, it can OHKO without being overcharged as much, but not when starting from zero charge.
**For example, a fresh fully charged Flare Blade will sufficiently overcharge a Hothead, but doing so in Training with stale moves disabled removes its ability to sufficiently charge it, as the additional 1.05x freshness bonus just barely grants Flare Blade enough damage to do so.

[[Boss Galaga]], [[Isaac]], [[Kyogre]]'s Hydro Pump and [[Oshawott]]'s Surf can [[push]] players into the side [[blast line]], but as they inflict no conventional knockback they are not considered one-hit KOs. The first one can also be easily escaped by button mashing at 0%.

====Stage hazards====
*Touching the hull of the [[Pirate Ship]].
*Touching the hull of the boat on [[Wuhu Island]].

While being hit by a [[Klaptrap]] on [[Jungle Japes]] causes a powerful [[meteor smash]] of OHKO power, it is otherwise unable to cause a conventional OHKO by the standards mentioned above. 

====Bosses====
The following will usually cause an OHKO on Hard [[difficulty]] only:
*[[Galeem]]'s Lens Flare with weaker or no [[spirit]]s (sweetspot, if most hits chain; not guaranteed).
====Other====
While inaccessible in a regular fashion without hacking, the gun found on the [[Stage#In_Ultimate_3|Free the Spirit screen's stage]] is programmed in as its own usable item, inflicting 25% damage with OHKO power. This situation is similar to ''Smash 4''{{'}}s Target Blast bomb.

{{#widget:YouTube|id=W5d-BGAls_s}}

====Video====
The following video demonstrates all the moves and hazards in ''Ultimate'' that inflict enough knockback to KO at 0%, alongside some powerful moves that don't. However, it also includes a few moves and hazards that do not inflict any knockback, such as [[Instant KO]]s:

{{#widget:YouTube|id=Y5IIRDd5ggY}}

===Conclusive video===
The following video demonstrates several one-hit KOs from every ''Smash'' game:

{{#widget:YouTube|id=y6_g2_FvFdA}}

==Trivia==
*In ''Brawl'': 
**This game alone features much more guaranteed OHKOs than all the other four games combined together: more than double (over 75%).
**The {{uv|Pokémon}} universe provides the highest number of OHKOs after the original ''Smash Bros.'' 
**22 out of 43 [[Pokémon]] physically appearing in this game are capable of OHKOs in some situations.
**{{uv|The Legend of Zelda}} universe provides the highest number of different [[Character|playable characters]] with OHKO potential ([[Zelda]] or [[Sheik]], [[Ganondorf]], [[Link]] and [[Toon Link]]). The ''Pokémon'' universe provides six characters with this ability, but only if [[Ivysaur]], [[Squirtle]] and [[Charizard]] are counted as separate characters instead of a single fighter (the [[Pokémon Trainer]]). 
**It is the only game where [[Assist Trophy|Assist Trophies]] can OHKO ([[Lyndis]], [[Knuckle Joe]] and [[Dr. Wright]] are severely [[nerfed]] in later games).
**16 out of 33 different [[Final Smash]]es (for 20 different characters) have OHKO potential if properly executed. The others can also KO at very low percentages.
*The [[Home-Run Bat]] is the only [[item]] (and by extension, the only attack) able to perform a guaranteed OHKO in every ''Smash'' game, at least on its [[sweetspot]].
*[[Roy]]’s [[Flare Blade]] and [[Counter]] are the only moves to maintain their OHKO power in every installment; like most [[sword]]-based hitboxes, they always require a [[sweetspot]] to land.
*At least one playable character from the {{uv|Fire Emblem}} universe possesses a move with OHKO potential in every game (either [[Marth]], [[Ike]], [[Lucina]] or [[Roy]]). Other main characters appear as [[item]]s with OHKO power (Lyndis in ''Brawl'' and [[Black Knight]] in ''[[Smash 4]]'').
*[[Marth]]'s [[Critical Hit]] is the only Final Smash to maintain its OHKO power in every installment. Throughout all games, it is also the most powerful attack of any character's standard moveset (in terms of knockback) without any exterior factors or buffs, being impossible to survive if in direct sight of a blast line, even on the largest stages of each game. In ''Brawl'' its strength is even higher.
*While the majority of OHKOs will fail to work on characters under the effects of a [[Super Mushroom]] or [[Metal Box]], a few attacks have such high knockback that it will still OHKO under these circumstances. Examples (in ''Brawl'' only) include [[Suicune]]'s Aurora Beam, [[Lugia]]'s Aeroblast, [[Jigglypuff]]'s [[Puff Up]], Marth’s Critical Hit, the [[Ultimate Chimera]]'s bite and several [[enemy]] and [[boss]] attacks (even on the lower [[Difficulty|difficulties]] for [[Tabuu]]'s [[Off Waves]]). 
**These attacks in ''Brawl'' have such immense knockback that it is possible for the main victim(s) to OHKO other opponents by simply knocking into them.
**Starting from ''Smash 4'', a few Final Smashes have hitboxes that negate the effects of such buffs, such as Marth's Critical Hit.
*Tabuu on Intense difficulty in the [[Subspace Emissary]] has more OHKOs than every other boss or enemy in all the ''Smash'' games, with 14. His OHKOs are reduced to 12 on Intense [[difficulty]] in [[Boss Battle]]s. In particular, despite losing its OHKO power, Ghost Projection is still very dangerous, being a guaranteed KO below 20%. Even more dangerous is Explosive Teleport, due to being extremely difficult to prevent (its OHKO potential forces the player to pay attention before attacking Tabuu).
**Considering Tabuu has only 16 attacks, 88% of his moves are potential one-hit KO moves.
**Tabuu has only one non-OHKO attack on Intense difficulty: Eye Lasers, that KOs well below 50%. Normal Teleport cannot harm the player in any way.
*Apart from Tabuu, other bosses that have a notable amount of OHKO moves (in ''Brawl'' only) include [[Duon]] (with 9), [[Galleom]] and [[Rayquaza]] (with 8 each), and both [[Master Hand]] and [[Crazy Hand]] (with 7 each plus 3 combined). All the other bosses in ''Brawl'' have 6 or fewer OHKOs.
**Combined Master Hand and Crazy Hand have access to 17 potential OHKO moves on Intense difficulty in ''Brawl'' (14 on Very Hard difficulty in ''[[Melee]]''), although some of them need multiple hits to connect to KO at 0%. This also results in their combined attacks occasionally being two OHKO moves.
**86% of [[Porky Minch]]’s moves (6 out of 7) and 80% of Rayquaza's (8 out of 10) are potential one-hit KO moves. However, Rayquaza's OHKOs are nearly always situational.
**Every main boss in ''Brawl'' (10 total) is capable of OHKOs under certain conditions, at least on Intense difficulty in the Subspace Emissary or [[Classic Mode]]. In Boss Battles, however, only 7 maintain this power.
*The most powerful moves in the ''Smash'' series are Tabuu's Off Waves (waves and contact with his body) on Intense difficulty in the Subspace Emissary and Boss Battles, and the Ultimate Chimera's bite in ''Brawl''. All these attacks deal 100%-200% damage and immense knockback. Off Waves are so strong that it OHKOs even on the Easy difficulty of the Subspace Emissary and Boss Battles (in the second case it is situational, but guaranteed on Normal and above).
*''Brawl'' introduced the trend of "final bosses" having extremely powerful attacks that feature waves in some form, and are usually an OHKO (on higher difficulties only, except for Tabuu). These include Winged Tabuu’s Off Waves, [[Master Core]]'s Blast Waves and [[Galeem]]'s Lens Flare (this one only situational).
*Master Core’s final explosion on 8.0 difficulty or above is the only OHKO that never KOs the player, since the battle is already won before the hitboxes land.
**Duon's Vacuum Spin, some of Porky Minch's attacks', contact with Porky Bots, Galleom's Tank Rush and Tank Rush & Slam can hit the player after the boss is defeated (with OHKO power on the higher difficulties) but, since the battle is already won, the player can never be KOed. However, the character could still be severely damaged in Boss Battles, turning successive hits in almost guaranteed KOs.
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