In Greek mythology, the King of Libya and ancestor of the great Perseus. He had fifty daughters while his brother, King Aegyptus, had fifty sons. In order to keep the sons, who wanted to marry the daughters, away from them he built a ship with fifty oars and fled to Argos, Greece. When they arrived, the inhabitants beheld the marvelous ship and, believing he was sent by the gods, made Danaüs their king.

Danaüs ruled in peace for many years before another splendid ship arrived at Argos, this time holding the fifty sons. Fearing for his life, he allowed them to marry his daughters. However, he gave a dagger to each one of his offspring and instructed them to kill their husbands the night they were to be married. All of them followed these instructions except Hypermnestra, who fell in love with her husband Lynceus and quickly fled the wrath of her father.

None of the forty-nine daughters could find husbands after their murderous actions, so each one of them died lonely. When they arrived at the underworld they were sentenced to forever carry water in sieves, trying in vain to fill a bath in order to wash off their sins. Because of this, Danaüs had no heir to his throne and was forced to send for Hypermnestra and her husband Lynceus, who became king and queen of Argos.