The Lich, also known as the Lich King, is the main antagonist of Adventure Time. He is an entity of pure evil who escaped from his imprisonment and tried to bring extinction to all life during his first appearance. He serves as a minor antagonist of Season 1, the main antagonist of Season 2, the overarching antagonist of Season 3, the main antagonist of Season 4, the Season 5 premiere arc, and Season 6 and a recurring antagonist of Seasons 7 and 8. He is Finn's arch-nemesis.
He was voiced by the legendary actor Ron Perlman, who also played Slade, Xibalba, Warhok in Disney's Kim Possible, Stabbington Brothers, Nino, Fire Lord Sozin, and Dieter Reinhardt.