Aeacus was a king of the island of Aegina in Greek mythology. He was a son of Zeus and the nymph Aegina, and the father of the heroes Peleus and Telamon. According to legend, he was famous for his justice, and after he died he became one of the three judges in the underworld alongside Minos and Rhadamanthus. In another story, he assisted Poseidon and Apollo in building the walls of Troy.