Aethlius (Ancient Greek: Ἀέθλιος) was, in Greek mythology, the first king of Elis, father of Endymion. He was the son of either Zeus and Protogeneia (daughter of Deucalion), and was married to Calyce. 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.