Perseus is the primary Greek example of the hero as monster slayer. He is also clearly marked as a hero by the fact that he was a son of Zeus. The myth begins in the Peloponnesus city of Argos, an ancient city founded by Danaus, who came to Greece from Egypt. The inhabitants of Argos were, therefore, called Danaans. Argos was ruled by Acrisius, who, even in his mother’s womb, fought with his twin brother Proetus. The fights continued into adulthood when Proetus attempted to take not only his brother’s kingdom, but also his daughter Danaë. War broke out between the twins, and Acrisius won. Proetus had to be content with ruling nearby Tiryns. When an oracle told Acrisius that Danaë would give birth to a son who would someday kill him, the king fell victim to the delusion that always affects those warned by oracles; he tried to outsmart fate. To prevent his daughter from having a son, he locked her away in a dungeon. This, of course, was not enough to prevent the always lecherous Zeus from penetrating the dungeon walls and entering Danaë herself in a shower of gold. The result of this miraculous act was the conception of Perseus, marking him from the beginning as a true hero. Acrisius refused to believe that his grandson had been conceived through Zeus and, in any case, he was not about to keep his predicted murderer in his court. Still, he feared the wrath of the gods if he killed his own daughter and her son, so he locked the mother and child in a chest, which he released into the sea. The chest washed up on the island of Seriphos, where the fisherman Dictys retrieved it and gave it to his brother King Polydektes, to raise Perseus.

Later, when Polydektes attempted to marry Danaë, he and Perseus became enemies.

When Polydektes pretended to be willing to marry another woman and demanded wedding presents, Perseus promised to bring him the monstrous Medusa’s head.