card Three-headed dog (Cerberus analogue) fromPhilosopher's Stone. Massive, three snarlingheads, immense size. Guardian of sacredthresholds echoing Greek Cerberus at theUnderworld. Embodiment of fear and loyalty:terrifying yet soothed by music. Monster asgatekeeper, requiring knowledge/ritual topass. Belongs to Hagrid, guarded the trapdoorto the Philosopher's Stone chamber. Defeatedby the ritual of lullaby.