In Greek and Roman mythology, Glaucus (/ˈɡlɔːkəs/; Ancient Greek: Γλαῦκος Glaukos means "greyish blue" or "bluish green" and "glimmering"), usually surnamed as Potnieus, was a son of Sisyphus whose main myth involved his violent death as the result of his horsemanship.
By his wife, Glaucus became the father of Alcimenes (Deliades or Piren) who was unintentionally murdered by his own hero brother.
[15] In one, he feeds his mares on human flesh in order to make them fierce in battle, but at the games he has no supply for them, and they turn on their master and devour him instead.
[6][16][17] Servius, however, regards Glaucus as a doublet of Hippolytus: he offended the goddess Aphrodite (Venus) either by keeping his mares from mating in order to preserve their speed,[6][18] or by scorning her in general.
[20] In other sources, the mares are driven into their man-killing frenzy by consuming either an herb in their Boeotian pasture at Potniae[6][21] or water from a toxic well.