Booko is a character who appeared in the episode "The Lich. He only appeared in a hologram right in front of Finn and Jake and talked about the multiverse. He also appeared in the episode "All the Little People" as one of the small people.
Appearance[]
He looks very similar to Key-per and the Door Lord. His body is yellow and he has a blue book hat on his head. He also wear a blue robe.