As the eighth bosses, Master Hand and Crazy Hand guard the Mirror Shard of Candy Constellation. Defeating them after the other shards have been collected allows Kirby to enter the true final level: the Dimension Mirror.
In Kirby & The Amazing Mirror, Master Hand is, together with Crazy Hand, the main boss of level 9, Candy Constellation. In addition, Master Hand appears as a recurring mid-boss throughout the game that gives the Smash ability (which gives Kirby the ability to use his moves from Super Smash Bros. Melee) to Kirby when eaten. Some of Master Hand's attacks in this game are taken directly from his attacks in the Super Smash Bros. series, and even has the same pose as in those games. Beating the duo gives Kirby the eighth and final Mirror Shard.
As a mid-boss, Master Hand has a total of four attacks, each of which are vaguely based off his moves from the Smash Bros. series. These attacks are pounding the ground with his fist, shooting out flaming bullets, punching Kirby, and forcefully seizing him. As bosses, Master Hand and Crazy Hand retain some of their tag team-based moves from Super Smash Bros. Melee, such as clapping and fist-pounding. Not counting their combination attacks, Crazy Hand employs the same exact moves and tactics that the regular Master Hand uses.
Master Hand's stars and projectiles can be swallowed to get different abilities. When Master Hand pounds the ground, stars are produced that grant Kirby the Stone ability. The bullet-like fireballs that Master Hand shoots give Kirby the Burning ability.
In the Super Smash Bros. series
Master Hand was originally a boss character in Super Smash Bros. long before his first Kirby universe appearance. Since then, he has appeared as the final boss of Classic Mode in every game in the Smash Bros. series. His counterpart, Crazy Hand, made his first appearance in the second installment, Super Smash Bros. Melee. Master Hand also plays an important role near the end of the Subspace Emissary in Super Smash Bros. Brawl, where he is manipulated by the malevolent entity Tabuu.
In Super Smash Bros. for Nintendo 3DS and Wii U, Master Hand reappears again in Classic Mode. However, if the player chooses an intensity higher than 5.0 and chooses to fight Master Hand and Crazy Hand, the fight is cut short upon dealing enough damage to the duo, as Crazy Hand will dematerialize while the entity named Master Core bursts out from Master Hand's glove. Master Core is made up of black particles called "Swarm," which can form into various objects/entities. These entities are Master Giant, a gigantic humanoid; Master Beast, a demonic dog-like creature; Master Edges (Master Sabres in PAL regions), a giant sword-like creation with four smaller variants; Master Shadow, a shadow clone of the player; and Master Fortress (in the Wii U version only), an eerie fortress that the player must trek through and destroy.
In Super Smash Bros. Ultimate, there are seemingly hundreds of Master Hands shown during the opening to World of Light, in which Marth comments that each of the fighters would need to take down about ten. The Master Hands all dissolve into energy and feed said energy into their master, Galeem, who obliterates every fighter except Kirby, thanks to Shulk seemingly warning him in advance. Master Hand can be seen on the world map from time to time, destroying bridges that players would use to easily find certain items.
Master Hand has the same primary attacks from game to game, although they are sometimes preformed differently and deal different damage. By teaming up with Crazy Hand, he can also preform devastating and hard-to-avoid combo attacks.
Master Hand is noteworthy in these games because he has the same premise and uses some of the same attacks that Wham Bam Rock used in Kirby Super Star. Wham Bam Jewel, who appeared in its remake, uses some of Master Hand's attacks as well.
Master Hand is a levitating, animated white glove. He is never seen on the ground except for when performing an attack. He can perform many hand-based attacks, such as punches, slaps, grabs, and sweeps. He is portrayed as a right hand, who many seem to consider the manifestation of creative spirit. Master Hand even uses long ranged attacks like shooting bullets and laser beams. He can also make combined attacks with his left-handed counterpart, Crazy Hand. Compared to Crazy Hand, Master Hand is the more submissive of the two.
|“||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.”|
|— Trophy description • Super Smash Bros. Brawl|
|“||The mysterious Master Hand is the source of creation in the Smash Bros. universe. He appears in Final Destination when all other rivals are defeated. He fights with a diverse move set and only grows stronger if you make him angry. If you know when to fight and when to dodge, you'll take him down!”|
|— Trophy description • Super Smash Bros. for Nintendo 3DS and Wii U|
|“||This sinister being will appear from Master Hand. A bunch of black objects, called "Swarm," will gather and mimic a variety of shapes, changing its attack pattern with each new form. After taking enough damage, it will reveal even more forms. Defeat the Swarm's forms to reveal its true core.”|
|— Master Core Trophy description • Super Smash Bros. for Nintendo 3DS and Wii U|
- Uja from Kirby: Squeak Squad can take the form of a glove, which greatly resembles both Master Hand and Crazy Hand.
- Of the bosses that have no eyes, Pix, Master Hand and Crazy Hand are the only ones that aren't mechanical.
- Master Hand makes a cameo appearance in Kirby: Planet Robobot as one of the Stone ability's transformations, though it can only be produced by the Smash Bros. Stone Change or Stone Smash moves. It is one of the rare Golden Statue transformations.