Three-headed doggy fan art & mythology

Cerberus

A three-headed dog guarding the exit from the underworld in Hades; the offspring of Typhon and Echidna.

He prevents the dead from returning to the world of the living, and the living from visiting the dead.

In one myth, the dog was enchanted by the singing of Orpheus, who descended into Hades for his wife Eurydice. The abduction of Cerberus was the last feat of Hercules. The hero descended into the underworld, received permission from the gods of the underworld to bring out the three-headed dog on the condition that he could defeat it with his bare hands. Hercules was able to tame Cerberus, after which he brought him to Eurystheus and, having shown the monster to the Mycenaean king, returned him back to the world of the dead.

And the drawing