Voiced by: Chikao Ōtsuka (Japanese), Hamilton Camp (English)
Unlike the rarely appearing mafia donnish Moriarty in the books, this Moriarty is portrayed as working personally on his plans without any sort of support network and frequently encountering Hound and his allies, being the antagonist in the majority of the episodes. Still an intellectual, he is a master inventor, often the one responsible for the steam punktechnology seen in the show, including his personal "steam car", which is more like a cross between a tractor and a tank than a car. His plans can occasionally be very complex or outlandish that rely on one questioning or linking together unusual acts, which is often how Hound figures out what Moriarty is up to. Sometimes he acts as a mercenary to other criminals who are after what he normally wouldn't steal. In this version, Moriarty resembles a gray wolf.