Houndoom are canine-like Pokémon, with a similar appearance to its pre-evolved form Houndour. Houndoom are large, black, and have a brown underbelly and muzzle. Around each of its ankles are two sets of bone-like bands. On its back are rib-like structures, appearing like an exoskeleton, that lead up to its neck. In between the two ends of the bone on its neck is a small skull emblem. Instead of having visible ears near the top of its head, Houndoom have large demon-like horn. Another notable feature is the long, skinny tail which ends in an arrow point.