The creature known as the guardian of the gates of the Underworld in various mythologies is often depicted as Cerberus in Greek myth. This three-headed dog ensures that the dead do not escape while preventing the living from entering without permission. Cerberus symbolizes the barrier between the living and dead, embodying themes of protection and fear. His presence adds to the ominous atmosphere of the Underworld, reflecting the inevitable reality of death and the afterlife in human mythology.