Perseus is among the oldest and most purely heroic figures of Greek myth, the son of Zeus by the mortal princess Danae, whom the god visited as a shower of golden rain in the bronze chamber where her father had shut her to forestall a prophecy that her son would kill him. Set an impossible task, to fetch the head of the Gorgon Medusa, whose gaze turned the beholder to stone, Perseus succeeds through divine aid and ingenuity: winged sandals, a cap of invisibility, and, crucially, the polished shield of Athena, in which he watches Medusa's reflection so as never to meet her eyes directly, and beheads her.
Returning with the head as a weapon that petrifies his enemies, he rescues the princess Andromeda from a sea-monster, and at last fulfils the prophecy by accidentally killing his grandfather with a discus. His myth is the template of the monster-slaying quest that later shaped the legend of Saint George and countless others, and the Greeks made him the ancestor of the heroic line of Mycenae and, through his descendants, of Heracles himself. He and several figures of his story were set among the constellations, fixing the myth in the night sky.