Aethlius was the son of Zeus and Protogeneia, the daughter of Deucalion. He was the first king of Elis. He was married to Calyce and was the father of Endymion.
According to some accounts, Endymion was himself a son of Zeus and first king of Elis. Other traditions again made Aethlius a son of Aeolus, who was called by the name of Zeus