Oxylus was a mythical king of Elis who came from Aetolia, called the son of Haemon (descended from Thoas) or, in another account, of Andraemon. An exile for unintentional homicide, he became the oracle-appointed guide of the Heraclids: matching the prophesied "man with three eyes" because he rode a one-eyed horse, he led Temenus and Cresphontes into the Peloponnese and in reward received the land of Elis. He is to be distinguished from the homonymous Oxylus, son of Ares.
Adapted from Wikipedia, "Oxylus (son of Haemon)" · CC BY-SA 4.0
I.Family
Oxylus came from Aetolia and is most often called the son of Haemon, who was himself the son of Thoas; an alternative tradition makes him the son of Andraemon. His Aetolian line was reckoned akin to the Heraclids.
By his wife Pieria, Oxylus fathered two sons: Aetolus, who died before his father and was buried near the gate of Olympia, and Laias, who succeeded him. A later descendant, Iphitus, was credited with restoring the Olympic Games, an event some scholars connect with 779 BC.
II.Mythology
Oxylus was driven into exile from Aetolia after committing an unintentional homicide; his victim is named in different accounts as either his brother Therimus or a man called Alcidocus.
While traveling, he met Temenus, son of Aristomachus, who had received an oracle instructing him to seek out "a man with three eyes" as a guide. Oxylus answered the riddle because he rode a one-eyed horse (or mule), so that horse and rider together had three eyes.
Oxylus joined Temenus and Cresphontes in their invasion of the Peloponnese, advising them to cross by sea from Naupactus to Molycrium rather than over the isthmus. In exchange for his help he asked for the land of Elis. Suspecting that the Dorians would covet so fertile a country once they saw it, he led them through Arcadia instead.
III.The contest for Elis
A dispute over the land arose with the Dorian Dius. To settle it, each side put forward a single champion: Degmenus, an archer, fought for Dius, and Pyraechmes, a slinger, fought for Oxylus. Pyraechmes prevailed and so secured Elis for Oxylus. Strabo gives a variant in which the opponents were the native Epeans rather than Dius.
Having won the country, Oxylus settled Aetolians in Elis and allowed Dius to live there with special privileges. He gathered the surrounding villages into the city and, in obedience to a prophecy, invited Agorius, a descendant of Pelops (counted a great-grandson of Orestes), to be co-founder, after which Elis prospered.
The Dorians swore an oath never to invade Elis, a custom later connected with the sacred truce of the Olympic Games; Elis is said to have remained without defensive walls until Pheidon of Argos broke the oath.
IV.Descendants
Through his son Laias the royal line of Elis continued, and the restoration of the Olympic Games was ascribed to his descendant Iphitus.
A family claiming descent from Oxylus is documented as existing at Elis from the fourth century BC down to AD 157, marking him as the legendary ancestor of a long-lived Elean house.