The hook man is one of the students in Mark Lilly's class. His name has never been addressed in the series. He has a large hook for his head, and each of his arms also ends in a single hook instead of a hand. He has gray skin, an anchor tattoo on his right shoulder, and a slight belly. He often wears a red and white striped tank, dark green shorts and red shoes. He never speaks nor communicates with others.

The hook man first appears in the episode "An American Werewolf in America". When Mark is talking about the importance of trust in the class, the fish man Toby says, "That's nice in theory, but you can't trust everybody" and gives the hook man a side way glance. The hook man only attends Mark's class occasionally.