Every Mythical Creature That Lives in Another Realm Explained in 34 Minutes

Cerberus is the original bouncer of the ancient world, and he's never once let anyone leave. In Greek mythology, this three-headed dog stands guard at the entrance to Hades, the realm of the dead, allowing souls to enter freely but tearing apart anyone foolish enough to try walking back out. His parentage alone tells you everything about his nature — he is the son of Typhon and Echidna, two of the most terrifying beings in all of Greek cosmology.