Hellhound

Goddess Hel and the hellhound Garmr by Johannes Gehrts, 1889

A hellhound is a mythological hound that embodies a guardian or a servant of hell, the devil, or the underworld. Hellhounds occur in mythologies around the world, with the best-known examples being Cerberus from Greek mythology, Garmr from Norse mythology, the black dogs of English folklore, and the fairy hounds of Celtic mythology. Physical characteristics vary, but they are commonly black, anomalously overgrown, supernaturally strong, and often have red eyes or are accompanied by flames.