Cerberus is a mythical creature from ancient Greek mythology, often depicted as a three-headed dog. He guards the entrance to the Underworld, ensuring that the souls of the dead do not escape and that the living do not enter without permission. Each of his heads represents a different aspect of life and death, making him a powerful symbol of the boundary between the two realms. In stories, Cerberus is known for his fierce loyalty to Hades, the god of the Underworld. Despite his intimidating appearance, he can be calmed with music or treats, showcasing a softer side. This duality makes Cerberus a fascinating figure in mythology, embodying both fear and protection.