Medusa was originally a ravishingly beautiful maiden, "the jealous aspiration of many suitors," priestess in Athena's temple, but when she was caught being raped by the "Lord of the Sea" Poseidon by Athena's temple, the enraged Athena transformed Medusa's beautiful hair to serpents and made her face so terrible to behold that the mere sight of it would turn onlookers to stone. In Ovid's telling, Perseus describes Medusa's punishment by Minerva (Athena) as just and well earned.
Her death in most versions of the story, she was beheaded by the hero Perseus, who was sent to fetch her head by King Polydectes of Seriphus. In his conquest, he received a mirrored shield from Athena, gold, winged sandals from Hermes, a sword from Hephaestus and Hades' helm of invisibility. Medusa was the only one of the three Gorgons who was mortal, so Perseus was able to slay her while looking at the reflection from the mirrored shield he received from Athena. During that time, Medusa was pregnant by Poseidon. When Perseus beheaded her, Pegasus, a winged horse, and Chrysaor, a golden sword-wielding giant, sprang from her body.
Head of Medusa, gate of the Royal Palace of TurinJane Ellen Harrison argues that "her potency only begins when her head is severed, and that potency resides in the head; she is in a word a mask with a body later appended... the basis of the Gorgoneion is a cultus object, a ritual mask misunderstood."