Three-headed dog

Three-headed dogs are very rare creatures. It is a giant dog with, as its name implies, three heads. Music appears to put them to sleep. Rubeus Hagrid owned one of these creatures; he named his Fluffy. It is unknown if all three-headed dogs fall asleep when they hear music, or just Fluffy. It is also unknown, if like the Runespoor, each of the dogs three heads served a different purpose.