Master Hand

"A being tied to the link between this world, where trophies fight, and the world beyond. The meaning of his existence is unknown, as are his goals, but he seems to have obtained (and kept hidden) a power that borders on absolute. He also seems to feel a certain joy in challenging chosen warriors who've claimed many victories. He waits even now in Final Destination."

- Master Hand's trophy description in Super Smash Bros. Brawl.

Master Hand, also known as "The Hand", is the central antagonist of the Super Smash Bros. series. He is a mysterious entity who created the Smash Bros. universe who seeks to beat all who challenge him. He also appears as the final boss of Classic Mode in every game in the series.

He is voiced by Jeff Manning in the original, Dean Harrington in Super Smash Bros. Melee, Pat Cashman in Super Smash Bros. Brawl, and Xander Mobus in Super Smash Bros. for Nintendo 3DS/Wii U.

Super Smash Bros.
Master Hand first appears in the opening cutscene of the game, where he takes plush dolls of two random characters and places them on a table. After setting up the objects around them, he counts to three and snaps his fingers, changing the table into the Peach's Castle stage and bringing the dolls to life.

Master Hand later appears as the final boss of the 1P Game. He attacks the player with slaps, punches, and flicks, and must be defeated by depleting his 300 hit points that must be depleted. Once all of his hit points have been depleted, he explodes while floating away into the background, along with the screen fading to white then fade to pitch black.

Afterwards, the player's character returns to their plush doll form. As the camera zooms out, the screen suddenly transitions to black, and the sound of a closing door plays.

Super Smash Bros. Melee
Master Hand once again serves as the final boss of Classic Mode. He has a few more moves than he had in the original, and his hit points depend on the difficulty. On normal difficulty or higher, once Master Hand health is reduced by half, Crazy Hand joins in. In the event matches, both Master Hand and Crazy Hand are the enemies of "Event 50: Final Destination Match".

Super Smash Bros. Brawl
In the Subspace Emissary of Super Smash Bros. Brawl, Master Hand commanded two of the main villains, Bowser and Ganondorf. However, he was being controlled by Tabuu. When Tabuu turned Ganondorf into a trophy, Master Hand's chains were broken and he attacked Tabuu, who easily defeated Master Hand.

Super Smash Bros. for Nintendo 3DS/Wii U
In Classic Mode of Super Smash Bros. for the Wii U and 3DS, if the player can choose to confront either Master Hand, or Master Hand partnering with Crazy Hand on Intensity 3.0 and higher. In Intensity 5.1 and higher, when they lose a good portion of their health, the two combine to form the Master Core.

Super Smash Bros. Ultimate
In the new adventure mode "World of Light", a swarm of Master Hands are the minions of Galeem. In the opening cinematic, the Master Hands break open to reveal balls of light, which are absorbed by Galeem to create lasers that destroy all of the fighters except Kirby. Master Hands also appear in the mode's overworld map, serving as either hazards or bosses.

Other games
After his first appearance in Super Smash Bros., Master Hand appears in some of the Kirby games, such as Kirby and the Amazing Mirror, where he and Crazy Hand are the bosses of Level 9, "Candy Constellation".

Trivia

 * Master Hand stars in the original Super Smash Bros. opening, as he sets up the stage and characters, and he is the first Smash character ever seen. This has been a part of the game's controversy over the fighters being "toys", either being brought to life by a child's imagination, or that Master Hand had brought them to life with his "Create" powers.
 * Since the Announcer never speaks when the player fights Master Hand, it is speculated that Master Hand is, in fact, the Announcer.
 * This is supported by the fact the voice actor of the Announcer, regardless of which Smash game, also voices Master Hand, as well as Crazy Hand in Melee and Brawl.
 * They are voiced by Jeff Manning in Super Smash Bros., Dean Harrington in Super Smash Bros. Melee, Pat Cashman in Super Smash Bros. Brawl, and Xander Mobus in Super Smash Bros. for Nintendo 3DS and Wii U.
 * The Chains of Light leave bloody wounds on Master Hand, suggesting that he may contain organic material. Interestingly, he seems to have glowing blue blood, even though his wounds are red. The revealing of blood could be a factor in the reasons why Brawl was rated "T for Teen" by the ESRB and rated "PEGI 12" by PEGI. However, the concept of the blue stuff being blood is gamer speculation.
 * Many gamers like to assume Master Hand "died" in Subspace Emissary, but this is highly unlikely as Master Hand has appeared in every Super Smash Bros. game and will most likely continue to appear in the series. It is more likely Master Hand passed out from the burns.
 * However, the Subspace Emissary seems to be the only "mainstream" continuity in the Super Smash Bros. games, which each have their own Classic Mode that can be played with any character.
 * If Master Hand (or Crazy Hand, for that matter) is KO'd on Brinstar in Melee via Debug Menu, he bounces endlessly on the acid. Using the developed mode camera, he can be seen bouncing away even once he leaves the stage and is in the black void behind the stage. It's interesting to note that the acid programming goes out this far. Since the vertical position of a portion of the acid does not depend on its horizontal position, however, it is possible that only the current height of the acid is used to calculate player damage, in which case the acid programming would go out infinitely far horizontally speaking.
 * In Super Smash Bros. Melee, if either Master Hand or Crazy Hand gets a transformation item (i.e. Super Mushroom, Starman, etc.), there is a chance the game freezes.
 * Master Hand and Crazy Hand may have originated from certain bosses in Super Mario 64, Star Fox 64, Kirby's Nightmare in Dream Land, Kirby Super Star, and The Legend of Zelda: Ocarina of Time as attacks used by Master Hand and Crazy Hand are similar to the attacks used by Eyerok, Wham Bam Rock, Andross, and Bongo Bongo.
 * In Super Smash Bros., Master Hand was much more glove-like in shape, but in Melee and Brawl, he looks more like an arm which fades on the wrist.
 * Master Hand and Crazy Hand are the only characters in the Super Smash Bros. series to debut in a game from that series, but also appear in another series. They also appeared in Kirby & the Amazing Mirror, both of them being bosses.
 * Master Hand appears in the commercial for Kirby Tilt 'n' Tumble (2000 in Japan, 2001 in North America), where he is holding the Game Boy Color, controlling the game.
 * In Super Smash Bros., Master Hand was much more glove-like in shape, but since Melee, he looks more like an arm which fades on the wrist.
 * Master Hand and Crazy Hand are the only characters in the Super Smash Bros. series to debut in a game from that series, but also appear in another series. They also appeared in Kirby & the Amazing Mirror, both of them being bosses.
 * Interestingly, the announcer has an announcement for Master Hand like he does for all other characters, although this is never used in-game. He does not, however, have a narration for Crazy Hand, although he does for Giga Bowser.
 * These are presumably for if either characters were to be displayed in the VS. screen, much like in Smash Bros. 64.
 * He does announce Master Hand and Crazy Hand in Super Smash Bros. for Wii U.
 * In Smash Bros 4, it is unknown if Tabuu, the entity that was original in control of Master Hand, still is controlling the hand during these events. This is most unlikely, as Tabuu was destroyed, and Subspace Emissary seems to be a separate continuity from Classic Modes (which seem to have very little continuity themselves).
 * It is possible for Master Hand and Crazy Hand to fight each other in a match. However, this will cause the game to freeze after the battle ends.