One of the most iconic characters in ancient Greek mythology, Medusa, whose name means guardian or protectress, was a winged female monster. A Gorgon. Instead of hair, she had hissing venomous snakes. Anyone who looked at her face would be petrified - literally turned into stone.
But Medusa had another life before being a Gorgon. She had been a beautiful young girl, who, after being seduced by Poseidon in Athena's temple, was transformed by Athena into a hideous monster.
She was eventually beheaded by the hero Perseus, who managed to avoid being turned into stone, thanks to various gifts from the gods: Athena gave him a polished shield so that he could avoid looking straight at Medusa; Hermes gave him winged sandals; Hephaistos gave him a sword, and Hades a helmet of invisibility.
When she died, Medusa was pregnant by Poseidon, so when Perseus beheaded her, Pegasus the winged horse emerged.
Medusa's image, in the form of her severed snake-haired head, became known as a Gorgoneion. It formed a central element in the aegis shared by Zeus and Athena, and developed as an apotropaic symbol, designed to ward off evil.