The Lich, also known as the Lich King, is the main antagonist of the cartoon series Adventure Time. He is an ancient undead entity who attempts to bring extinction to all life in the multiverse as well as the arch-nemesis of Finn.
Not much is known about the origins of the Lich, but it is hinted that he was created by GOLB and sent to Earth as a Catalyst Comet, to destroy all life for him. He was one of the monsters before time existed.
Early on, the Lich had a plan to suck all life from the Land of Ooo. Using the stolen power, he planed to destroy all life, but he was attacked by the hero Billy. He was trapped in a prison of amber in the heart of the Candy Kingdom after Billy personally pounded him into it.
And he is reprised by Ron Perlman in the English dub and Hiroo Sasaki in the Japanese dub.