Crazy Hand is the secondary antagonist of the Super Smash Bros series, and is Master Hand's left hand and brother. While Master Hand's movements are very relaxed and easygoing, Crazy Hand moves in dysfunctional and erratic ways. To fight him in Super Smash Bros. Melee, you have to clear Normal level Classic Mode in 18 minutes or less and reduce Master Hand's health by half. If the player loses the match and opts for continuing, though, Crazy Hand will not be fought in the retry. He also appears in Event 50: Final Destination Match.
Crazy Hand looks exactly the same as Master Hand (apart from being a left hand), but is more chaotic in general. He is impulsive and destructive. When preparing for an attack, Crazy Hand's movements are also different. When joined with Master Hand, they can perform several cooperative attacks that usually do 1.5-2 times as much damage.
Though he appears in Super Smash Bros. Brawl during the Boss Battles mode, he does not actually appear as a boss of the Subspace Emissary. Despite this, his trophy, when arranging your collection by series, is listed in the "The Subspace Emissary" section. Aside from this, though, he merely reprises his role in Classic Mode, and has no relation to SSE, despite the fact that Master Hand appears. To fight him in Classic Mode, you must arrive at the final stage in 9 minutes or less with the difficulty level set to Hard or above. He also appears as one of the many bosses in Boss Battles.
In Super Smash Bros. for Nintendo 3DS and Wii U, he can be fought in Classic Mode by taking the black path on the final path to stage 6 on Intensity 3.0 or higher (3DS) or if certain conditions are met (Wii U), where he will assist Master Hand at the start of the battle. He will also be the final enemy of Crazy Orders (exclusive to the Wii U version), where will fight alone or accompanied by CPU characters in a Stamina match against the player; and will randomly drop treasure chests containing rewards as he receives damage. Crazy Hand's origins are unknown, and the two Hands are in a dualistic conflict of create (Master Hand) and destroy (Crazy Hand).