Cerberus in Greek and Roman mythology, is a multi-headed (usually three-headed) dog, or “hellhound” with a serpent’s tail, a mane of snakes, and a lion’s claws. He guards the entrance of the Greek underworld to prevent the dead from escaping and the living from entering.
Cerberus is featured in many works of ancient Greek and Roman literature and in works of both ancient and modern art and architecture, although the depiction of Cerberus differs across various renditions. The most notable difference is the number of his heads: Most sources describe or depict three heads; others show Cerberus with two or even just one; a smaller number of sources show a variable number, sometimes as many as fifty or even a hundred.
Cerberus is the offspring of Echidna, a hybrid half-woman and half-serpent, and Typhon, a gigantic monster even the Greek gods feared. Its siblings are the Lernaean Hydra; Orthrus, a two-headed hellhound; and the Chimera, a three-headed monster. The common depiction of Cerberus in Greek mythology and art is as having three heads. In most works, the three heads respectively see and represent the past, the present, and the future, while other sources suggest the heads represent birth, youth, and old age. Each of Cerberus’ heads is said to have an appetite only for live meat and thus allow only the spirits of the dead to freely enter the underworld, but allow none to leave. Cerberus was always employed as Hades’ loyal watchdog, and guarded the gates that granted access and exit to the underworld.
Cerberus painting by William Blake, 1824-1827