In Greek mythology, Aeacus was king of Aegina island in the Saronic Gulf. He was very famous in the true sense of piety and justice with which he ruled his people and their judgments were sought from all over Greece, so that after his death he was appointed judge of the shadows in Erebus, along with the Cretans Minos and Rhadamanthys. A further elaboration of the myth that Rhadamanthys judged the souls of the eastern Aeacus those of the Hellenes (European) and Minos had the decisive vote
Aeacus was the son of Zeus and Aegina, daughter of the river god Asopus, so birth linked to Olympians with chthonic water spirits of the country. His mother was taken by Zeus to the deserted island of Oenone, who since then was named: Aegina. It was one of the favorite sons of Zeus, to the point he tried to make him immortal, but the Fates (the target) was prevented.
Realizing the infidelity of Zeus, Hera, his wife, sent a terrible plague that decimated the population of the island. Aeacus prayed to his father Zeus asking for help. The king of the gods became the ants of the island men, two who were called Myrmidons and later fight in the Trojan War.
His prayers to Zeus asking for rain at a time of drought were commemorated in a temple on the island Egina. himself erected a temple to Zeus and Poseidon and Apollo helped (who had been punished by Zeus) in the construction of magnificent walls of Troy for king Laomedon .
He had an affair with the nymph Psamathe, born of the ill-fated Phocus. Endeis later married Megara, which had to Telamon and Peleus heroes (father of Achilles). These, perhaps encouraged by his mother, killed his half-brother Phocus, so Aeacus, terribly affected, expelled from his kingdom. Such was the wrath of Psamathe when he learned that his son had been killed in revenge became a wolf that killed the cattle on the island of Aegina.
No other archaic of priest-kings who ruled Aegina is remembered by mythographers, because Aeacus grandchildren and children of Phocus, Crixus, Panopeus left the island and settled in Phocis, a region bordering the Gulf of Corinth, east Boeotian.
In Aristophanes' Frogs, descends to Hades and Dionysus appears as Heracles, making Aeacus laments the theft of Cerberus by this and ordered him to be tortured in the Acheron by the hounds of Cocytus, Echidna, the moray tartesia and tritasias the Gorgons.
Aeacus was the ancestor of the lineage of Eácidas. Alexander until he traced his ancestry through his mother.