in Greek mythology, a king of Argos, grandson of Danaus. He quarreled with his twin brother, Acrisius, and divided the kingdom with him, Proetus taking Tiryns, which he fortified with huge blocks of stone carried by the Cyclopes (Cyclops). Proetus had three daughters with Stheneboea (called Anteia in Homer's Iliad), the daughter of Iobates, king of Lycia. Proetus's daughters were driven mad either because they had insulted the goddess Hera or because they would not accept the new rites of Dionysus. They believed themselves to be cows and wandered the land, mooing. Finally, the seer Melampus cured them on condition that he be given a third of the kingdom and his brother, Bias, another third. (In another version, according to Bacchylides' ode 11, the daughters recover when Proetus prays to Artemis.) In Ovid's Metamorphoses, Book V, Proetus drives Acrisius out of Argos but is turned to stone when he sees Medusa's head, wielded by Perseus. See also Bellerophon.