In J.K. Rowling’s fantasy novel Harry Potter and the Philosopher’s Stone, Hagrid’s three-headed dog is named Fluffy.
Fluffy guards a trapdoor at Hogwarts as part of the protections surrounding the Philosopher’s Stone. Hagrid obtains the dog from a Greek man in a pub and keeps it in a restricted area of the school. Despite its frightening appearance, Fluffy can be lulled to sleep by music.
Harry Potter, Ron Weasley, and Hermione Granger discover Fluffy while investigating the mysterious protections around the Stone. They realize that the dog is guarding the trapdoor and later use music to get past it. The encounter establishes that Hogwarts contains several magical defenses, each designed to challenge intruders differently.
Fluffy is often confused with Fang, Hagrid’s large boarhound, but they are different animals. Norbert is Hagrid’s Norwegian Ridgeback dragon, while Aragog is the giant acromantula living in the Forbidden Forest. The name Fluffy is also a comic contrast with the creature’s dangerous role.