Lynkeus was the jealous murderer of Kastor, along with his brother, Idas. Idas and Lynkeus murdered Kastor because they all (along with Polydeukes) sought Phoebe and Hilaeira, daughters of Leukippus (who was also Idas and Lynkeus' uncle in some versions). Before murdering Kastor, Lynkeus was one of the Argonauts and he participated in the hunt for the Kalydonian Boar. He was a son of Aphareus and Arene and was said to have excellent sight, even able to see through trees, walls and underground.