Italy: Medusa as the shield of Athena. Oil on canvas painting by Michelangelo Merisi da Caravaggio (29 September 1571 - 18 July 1610), c. 1597. In Greek mythology Medusa (Greek: guardian, protectress) was a Gorgon, a chthonic monster, and a daughter of Phorcys and Ceto. Gazing directly upon her would turn onlookers to stone. She was beheaded by the hero Perseus, who thereafter used her head as a weapon until he gave it to the goddess Athena to place on her shield. In classical antiquity the image of the head of Medusa appeared in the evil-averting device known as the Gorgoneion.