Leukos was an old soldier. He caught wind of a plot by Echidna to kill Hercules and Alcmene and he traveled to find Hercules and warn him. He found Iolaus who asked him to wait at a location outside of town. Unfortunately, by the time Iolaus brought Hercules to meet him, Leukos had been killed. The heroes found his neck pierced by one of Hephaestus' arrows. Hera's Archers were working for Echidna and they had reached him first. "Leukos" means "white" in Greek.