Three-headed dogs are very rare creatures in the Wizarding World. It is unknown if, like the Runespoor, each head serves a different purpose. Their great weakness is the inability to resist falling asleep to the sound of music.
- Three-headed dogs are inspired by the legend of Cerberus, a beast from Greek mythology that guarded the gates to the Underworld and was Hades' pet.
- In the film adaptation of Harry Potter and the Philosopher's Stone, Hagrid gets Fluffy from "an Irish fellow". In the novel, Hagrid gets him from "a Greek chappie".