The Skull Kid is the main antagonist and Link's adversary In the Legend of Zelda: Majora's Mask. He is a very playful yet mischievous character from the Lost Woods (the same Lost Woods from Legend of Zelda: Ocarina of Time). After being ignored by his peers he makes it his duty to extract revenge on them through the power of Majora's Mask. However, the mask bears too large a burden, and eventually overpowers him. Being an instrument of evil, Skull Kid becomes the chief source of conflict in the game due to causing the Moon to inevitably crash into earth.
The Skull Kid is originally a friend of the Four Giants that help hold the Moon up at the end of Majora's Mask. Skull Kid becomes saddened by the eventual absence of the Giants, and is lead to play jokes and pranks on others as a primary source of pleasure. Before the events of OoT, Skull Kid steals Majora's Mask from the happy mask salesmen, all the while meeting with the fairies Tatl and Tael. Skull Kid continues on in an attempt to steal the Ocarina of Time from Link and sells his horse Epona to a ranch.
Skull Kid is thought to be a scarecrow, as his face seems to be made out of hay or wood, his arms portrayed as sticks, and has a scrawny build. However, it is said that a Skull Kid is what becomes of children that take a wrong turn in the Lost Woods.
The Skull Kid has multiple appearances in the Legend of Zelda series. However, it's unconfirmed if the same Skull Kid in Majora's Mask is the same one from OoT it is only hinted by text. Link first encounters Skull Kid in the Legend of Zelda: Ocarina of Time within the Lost Woods and teaches him "Saria's Song" symbolizing a start of a beautiful friendship between the two. It's also optional in OoT to sell masks to Skull Kid showing that he had an interest in them before the events in Majora's Mask. Following the events of OoT, Skull Kid emerges as a main character in the Legend of Zelda: Majora's Mask. Towards the end of the game he tells Link he smells the same scent as "that fairy kid who taught [him] that song in the woods." After the credits in the game "Saria's Song" will play hinting that it was the same Skull Kid. Finally, Skull Kid appears as a sub boss in the Legend of Zelda: Twilight Princess, once again leading Link around a forest flooded with twists and turns.
On December 6, 2013, Skull Kid was revealed as the first Assist Trophy for Super Smash Bros. 4 Wii U/3DS.