Medusa was a descendant of the ancient family of gods discussed by Hesiod in the Theogony. Gaia, the original Earth Mother, was her grandmother. Her parents were Phorkys, the “Old Man of the Sea;” and Keto, a sea monster. Medusa was not their only offspring, but she was the only mortal member of a set of triplets, the Gorgons. Other siblings included another set of triplets, the Graiae, and several monsters, including Thoosa, the mother of Polyphemos, the Cyclops blinded by Odysseus. The Graiae—the Grey Ones—were born with grey hair; they were personifications of the foamy waves, of the rough sea. The Gorgons (gorgos = frightening), were terrifying beings from whose belts hung lunging snakes. Of the Gorgon sisters, Medusa was the most famous and most feared. Homer said her head was “a thing of fear and horror.” Anyone who looked at her would be turned to stone.

In many ways Medusa was a victim of circumstance. Originally she had been a beautiful priestess of Athene, but she was raped by Poseidon and blamed for the act, as rape victims so often are, making Athene her eternal enemy. Athene turned the beautiful girl into a monster, a figure of horror with snakes for hair. Since Athene was Perseus’s half-sister (Zeus was their father) and hated Medusa for her own reasons, she decided to help Perseus on his quest. Athene warned Perseus never to look directly at Medusa lest he be turned to stone. She gave him a polished shield which he could use to see Medusa’s reflection without looking at her directly.

Hermes helped too; he gave his half-brother Perseus (Perseus and Hermes were both fathered by Zeus) a sickle with which he was to decapitate Medusa. Furthermore, his divine siblings told Perseus he would need a container called a kibisis in which to place the lethal head of Medusa; a helmet belonging to their uncle, Hades, to make him invisible; and winged sandals to make it possible for him to escape the Gorgons after his killing of Medusa. The Stygian nymphs were the guardians of this equipment, but only the mysterious Graiae sisters knew where the nymphs lived. The Graiae lived at the limits of the western world on the edge of night. They shared one eye and one tooth between them, passing the eye and the tooth from one to the other as needed. Perseus found his way to the Graiae home and snatched the eye and the tooth during one such transfer. The Graiae were understandably distraught. Perseus promised to return the tooth and eye if the Graiae would direct him to the nymphs. The sisters told him to go to the land of Hyperborea at the edge of the North Wind. There the nymphs gladly gave the hero the objects he needed and he descended to the end of the ocean, in effect the Underworld, where the terrible Gorgons made their home.

Equipped with the winged sandals, the kibisis, and the helmet of Hades, Perseus approached the sisters and found them sleeping. Apollodorus tells us that their heads were “twined about with the scales of dragons,” and that they had “great tusks like swine’s,” but also “golden wings.” The bodies of men turned to stone by the sight of Medusa surrounded the sisters. This was truly a Hell. Perseus approached Medusa, being careful not to look directly at her, using Athene’s shield as a mirror. Then, his hand guided by Athene herself, he used Hermes’ sickle to remove the monstrous head with one swipe. The winged horse Pegasus and the warrior Chrysaor, children of Medusa’s liaison with Poseidon, sprang from the Gorgon’s head. Pegasus would play a major role in the hero Bellerophon’s defeat of another monster, the Chimera. Chrysaor would father the three-headed monster known as Geryon, who played a role in the Herakles myth.