One-hit KO

A one-hit KO, commonly abbreviated as OHKO (also referred to as an Instant KO in Melee), is an attack in the Super Smash Bros. games with such high base knockback that it KOs an opponent at 0%. Such attacks currently exist in every installment of the series. However, moves with the potential to OHKO are not necessarily guaranteed to do so, and may fail to OHKO under the following circumstances:

• The opponent techs, DIs, utilizes momentum cancelling, and/or crouch cancels 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.
• Knockback may be insufficient to KO at 0% on very large stages (e.g. Temple, New Pork City, and 75m), or from the far edge of a stage.
• Knockback may be insufficient to KO at 0% if the attack had already been landed previously (due to Stale-Move Negation).
• Knockback may be insufficient to KO heavy characters at 0%.
• Opponents are under an effect that makes them more resilient (such as being giant, metal, or in an event that reduces the knockback they sustain), or the player is weakened (such as being tiny or given a lower handicap).
• The damage ratio is lower than standard, reducing knockback.

The general rule for a move to be considered a one-hit KO is being able to KO an average-weight character, such as Mario, at 0% damage from the center of Final Destination under standard conditions as mentioned above. 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 that inflict no knockback are not considered to meet the definition of one-"hit" KO's; for example, being flown off the screen by the Landmaster or eaten by the Summit's Fish or Distant Planet's Bulborb are not listed below.

In All Appearances

Items

• A smash attack with the Home-Run Bat.

In Super Smash Bros.

Moves that KO'd 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

• If Fox uses Reflector on a walking Bob-omb, that Fox player (as well as any character caught in the blast radius) will be OHKO'd.
• If 2 Foxes use Reflector on a Green Shell, it will eventually gain OHKO power after 3-4 reflects.

In Super Smash Bros. Melee

Unlike in Smash 64, there are multiple moves that can OHKO in Melee. They still remain rare however.

Playable characters' moves

• Roy's fully charged Flare Blade.
• Mr. Game & Watch's fully loaded Oil Panic after absorbing three strong projectiles (such as three PK Flashes).
• Roy's Counter upon countering an extremely powerful attack; a hitbox that deals around 35% damage will result in an OHKO if countered (such as a smash thrown Bob-omb).

Items/Enemies

• Getting caught in Lugia's Aeroblast (can whiff if the player is hit at the left or right endpoint of its attack).
• Touching Moltres.
• A thrown Polar Bear.

Stage hazards

• Banzai Bill's explosion on Princess Peach's Castle (if all hits connect).
• In 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.

In Super Smash Bros. Brawl

Brawl continued the trend of adding several OHKOs into the game. However, the majority are Final Smashes, items, stage hazards, or boss attacks, with very few being standard moves of playable characters.

Playable characters' standard moves

• Ike's stage 8 Eruption.
• Mr. Game & Watch's fully loaded Oil Panic after absorbing three strong projectiles (such as PK Flash).
• The following counterattacks:
  • Ike's Counter upon countering an extremely powerful attack (a hitbox that deals at least ~45% damage).
  • Marth's Counter upon countering an even more powerful attack (a hitbox that deals at least ~50% damage).

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.

Final Smashes

• Marth's Critical Hit.
• Ganondorf's Beast Ganon (if all hitboxes land). If a character paralyzed by Beast Ganon is not hit by the charge afterward, they can be inflicted with a meteor smash of OHKO power.
• Lucario's Aura Storm at full power when all hits connect.
• Zelda's Light Arrow (barely in OHKO threshold, easily DIed).
• Wario-Man's fully charged Wario Waft.

Items

• The Dragoon.
• Touching Moltres.
• Suicune's Aurora Beam.
• Deoxys's Hyper Beam, both the single initial blast and the following multi-hitting blast.
• Electrode's explosion after being smash thrown.
• Knuckle Joe's Vulcan Jab to Rising Break attack.
• If Wario runs over a buried Pitfall while riding on his Wario Bike, he will be sent flying at OHKO power.
• If an uncharged Hothead is hit by a fire-based hitbox that deals over 30% damage (such as Ike's stage 7-9 Eruption), it will OHKO when smash thrown. Any sparks it gives off while traversing the stage at this strength will also OHKO.
• If a Soccer Ball 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.

Stage hazards

• Touching the hull of the Pirate Ship.
• The Ultimate Chimera's bite.
• The first spike on Rumble Falls (can easily be teched).

In addition, getting crushed will instantly KO the player without them ever crossing the blast line, however it technically does not meet the definition of a one-"hit" KO as it inflicts no knockback.

Bosses

• Tabuu's Off Waves on Normal or higher difficulties in The Subspace Emissary, or on Very Hard and Intense difficulties in Boss Battles Mode.
• Tabuu's Golden Bracket and Chain of Light attacks on Intense difficulty in the SSE.
• Galleom's attack when he stiffens and falls on the player on Intense difficulty in the SSE.
• Galleom's tornado spin on Intense difficulty in the SSE (if most hits connect).

Video

The following video demonstrates all the moves and hazards that KO at 0% in Brawl:

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In Super Smash Bros. 4

Like Brawl, SSB4 continues to add OHKOs to the game.

Playable characters' standard moves

• Roy's almost fully charged and fully charged Flare Blade when sweetspotted.
• Mr. Game & Watch's fully loaded Oil Panic after absorbing three medium power projectiles or one very strong one.
• 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 Zelda's fully charged Phantom Slash.
• The following counterattacks:
  • Ike's Smash Counter and Shulk's Power Vision custom moves upon countering a hitbox that deals 30% damage or more.
  • 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.
  • Mii Swordfighter's Blade Counter upon countering a hitbox that deals 37% damage or more.
  • Lucina and Marth's Counter, Little Mac's Slip Counter, and Palutena's Counter 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, even to a character as light as Jigglypuff, KOing it only at 12%.

Final Smashes

• Marth and Lucina's Critical Hit.
• Giga Mac's fully charged Straight Lunge sweetspot, fully charged up smash when sweetspotted, and forward smash when angled up or horizontally.
• Wario-Man's fully charged Wario Waft.
• Captain Falcon's Blue Falcon.

Items/Enemies

• The Daybreak's sweet spot.
• The Dragoon.
• Electrode's explosion after being smash thrown.
• If the Hothead is powered up significantly (30% total or higher), it will gain OHKO power.
• 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.
• Smash attacks when boosted by the Black Knight item from Smash Tour.

The Beetle and Boss Galaga items can carry players past the upper blast line, but as they inflict no knockback they are not one-"hit" KOs and both can be escaped by button mashing.

Stage hazards

• Touching the hull of the boat on Wuhu Island.
• Touching the hull of the Pirate Ship.
• Odin's Zantetsuken attack on the Midgar stage.

There also exist the following instant KO hazards, though they do not meet the one-"hit" KO definition as they inflict no knockback:

• Getting crushed between the two halves of Midgar as the stage reforms.
• In Smash Run, touching an Orne.
• In Smash Run, touching a Danger Zone in some challenge rooms and in the Climb! and Run! Final Battles.

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

Bosses

• Master Core's final attack if the player does not defeat it in time (about 45 seconds).