Aeacus, in Greek mythology, son of Zeus and Aegina, the daughter of the river god Asopus; Aeacus was the father of Telamon and Peleus. His mother was carried off by Zeus to the island of Oenone, afterward called by her name. Aeacus was celebrated for justice and in later tradition became a judge of the dead, together with Minos and Rhadamanthys. His successful prayer to Zeus for rain during a drought was commemorated by a temple at Aegina, where a festival, the Aiakeia, was held in his honour.