Yen Sid is a powerful sorcerer originally from the "The Sorcerer's Apprentice" short in the Disney film Fantasia. He is a retired Keyblade Master, renowned for his wisdom and command over the arts of magic. Although he is no longer an active Keyblade Master, he still keeps a close watch on the balance between light and darkness. He was once Mickey Mouse's master, and taught him everything he knows of magic and the Keyblade. In this game, he was one of the warriors of light that fought against Dust of Osiris' forces of darkness in the great war of light and darkness.