An unlockable character is a character that is not available at the start of the game (unlike a starter character), but must be unlocked. A special criteria is needed in order to unlock a character. First, the player must do a special task, once the task is done, then a message will display "Warning! Challenger Approaching!" with a silhoutte of the character. The player must be then challenge and defeat the character to unlock the character. Template:Spoiler
Super Smash Bros.
Characters
| Character | How to Unlock |
| Captain Falcon | Beat the 1-player mode with any character on any difficulty level in less than 20 minutes. |
| Jigglypuff | Beat the 1-player mode wth any character on any difficulty level. |
| Luigi | Beat Target Test with all 8 starting characters in either 1-player mode or in practice. |
| Ness | Beat the 1-player mode with 3 lives, on normal difficulty, with any character, without continuing. |
Super Smash Bros. Melee
Characters
| Character | How to Unlock | VS Matches Required |
| Dr. Mario | Complete Classic or Adventure mode with Mario without using a Continue | 100 |
| Falco Lombardi | Clear 100-Man Melee | 300 |
| Ganondorf | Complete Event Match #29 (Triforce Gathering) | 600 |
| Jigglypuff | Complete Classic or Adventure Mode | 50 |
| Luigi | Complete Stage #1 of Adventure with time ending in a "2" | 800 |
| Marth | Play Classic Mode with all 14 regular characters, or use them in VS. mode | 400 |
| Mewtwo | Play VS. mode for a combined total of 20 hours* | 700 |
| Mr. Game & Watch | Complete Adventure & Classic Mode with all other characters, or Clear Target Test with all other characters | 1000 |
| Pichu | Complete Event Match #37 (Legendary Pokemon) | 200 |
| Roy | Complete Classic or Adventure mode with Marth | 900 |
| Young Link | Complete Classic Mode with 10 different characters | 500 |
Super Smash Bros. Brawl
Masahiro Sakurai once stated that he feels that it would be appropriate that third-party, or "guest" characters, like Solid Snake or Sonic the Hedgehog, would be unlockable. This became true when Super Smash Bros. Brawl came out on January 31.
Also, the Smash Bros. DOJO!! has confirmed that most unlockable characters will be unlockable by "playing through" The Subspace Emissary. The use of the phrase "playing through" possibly suggests that these characters will be unlocked as you progress through the mode, rather than after completing it. With the setup of the mode, as seen in the Brawl demo available at E For All, in consideration, it seems likely that secret characters will be unlocked either immediately before or after clearing their respective parts.
Characters
| Character | How to Unlock |
| Captain Falcon | Play through Classic Mode on Normal.(?) / Play 70 Vs. Matches |
| Luigi | Play through Classic Mode on Easy.(?) / Play 22 Vs. Matches |
| Ness | Play 5 Vs. Matches / Reflect 10 Projectiles / Subspace Emissary |
| Lucario | Subspace Emissary / Play 100 Vs. Matches |
| Falco | Complete 100-Man Brawl / Play 300 Vs. Matches |
| Robot | Subspace Emissary / Play 160 Vs. Matches |
| Toon Link | Subspace Emissary / Play 400 Vs. Matches |
| Marth | Play 10 Vs. Matches / Beat Classic Mode on any Level / Subspace Emissary |
| Mr. Game & Watch | Play 250 Vs. Matches |
| Ganondorf | Subspace Emissary |
| Sonic | Play 50 Vs. Matches |
| Snake | Play 10 Vs. Matches on Shadow Moses Island / Play 130 Vs. Matches |
| Jigglypuff | Play 350 Vs. Matches |
| Wolf | SSE - In the stage "Iseki" (Ruins) skip the first door you pass when being lowered in to the pit. Instead enter the second door at the bottom to unlock him / Play 450 Vs. Matches |
Footnotes
* Time required to unlock Mewtwo can be split between players (eg. 2 human players requires 10hrs, 3 human players requires 6hrs 40mins, and four players requires 5hrs).