The hero who killed Medusa was the son of Zeus and Danae. Perseus had been locked in a box together with his mother and thrown into the sea by her father king Acrisius of Argus, who had been told his grandson would kill him. Mother and son were rescued at the island Seriphos, where the king Polydectes fell in love with Danae. When Perseus was fully grown, the king sent him away to get Medusa's head so that he could have Danae all to himself.
Perseus went to the Grey Women, three witches that shared one eye between them, and through stealing it he made them tell him where the nymphs of the north lived. They gave him winged sandals, a magic bag that fit anything put in it and Hades' cap which made him invisible whenever he wore it. Hermes gave him an un-breakable sword, and Athena a shield.
With all this equipment, Perseus managed to kill Medusa by looking at her through the reflection of the shield and escaped her sisters by wearing the cap. His winged sandals flew him home. Later he offered Medusa's head to Athena.
On his way he saved princess Andromache from a seamonster and married her. On his return at Seriphos he turned king Polydeuctes to stone with the head of Medusa. They returned to Argos, where Perseus killed his grandfather by accident during a discus competition, fulfilling the prophecy.
Perseus was sometimes considered to be the forefather of the Persians through his son Perses.