Hellhounds are in the lowest-ranking tier of the hierarchy system, along with Imps. Because of this, the majority have a servitude role in Hell, being used primarily for labor or work to the point that their service is advertised by businesses.
All Hellhounds that have been seen so far, Loona and Vortex, are anthropomorphic demons that resemble canines or canine-like carnivorans, taking after one specific breed or species for their appearance, with Loona and Vortex looking like a wolf. Hellhounds thus far all share distinguishable ears, tails, and muzzles specific to their typing.
- Human Disguise: Hellhounds can don a human appearance on Earth. These disguises retain traits of their demon forms, such as the presence of Vortex's scarred eye.
- Enhanced senses: Hellhounds appear to have an extrasensory type of smell for tracking a target by sniffing an item that identifies them. Loona, for instance, smelled a hitlist of the humans for the Immediate Murder Professionals and could detect where they were by their scent.
- The hellhound is a folkloric creature tracing back to Greek mythology; described as a species of supernatural canid of the underworld, the hellhound traditionally features black fur, red eyes, and ghoulish characteristics. They are often assigned to tasks involving the afterlife, such as guarding the entrances to the world of the dead or hunting lost souls. Cerberus, the three-headed guard dog of the god of the underworld, Hades, was considered a hellhound. In post-classical European cultures, they were considered an omen of death.
- Hellhounds are one of the few species of demon shown to have visible ears, with the only other exception being certain damned former humans, such as Mrs. Mayberry, and a few succubi, featuring pointed ears.