Master Yen Sid

Master Yen Sid is a powerful sorcerer who made his Disney debut in  Fantasia. He appears in  Kingdom Hearts II,  Kingdom Hearts Birth by Sleep,  Kingdom Hearts coded and  Kingdom Hearts 3D: Dream Drop Distance as a retired  Keyblade Master, renowned for his wisdom and command over the arts of magic; though no longer an active Keyblade Master, he still keeps a close watch on the balance between  Lightand  Darkness. He was once  Mickey Mouse's master, and taught him everything he knows of magic and the Keyblade.