Hair Apes appear in the episode "Dungeon Train" as challenges on the train. After rubbing their hands together, they can shoot blue bolts of electricity out of their hands and direct it toward their target. Their shocks are not of a high enough voltage to kill; one catches Finn off guard and zaps his head, but this leaves no visible injury. When struck, they disappear, leaving behind only hair. They communicate by hooting, a language which Jake can apparently understand.
Shaggy brown hair completely covers their bodies, even their eyes. They have big mouths, teeth, and lips. One of them wears a gold crown, and another has a blue turban with a red gem. The one Finn shoots a bolt at wears a gold headband with white wings. The one Jake sits with on the top of the train wears a small conical blue hat with a crescent moon on it.