In Greek mythology, Erginus was king of Minyan Orchomenus in Boeotia. He was the son of Clymenus, his predecessor, and Buzyge (or Budeia); his brothers were Arrhon, Azeus, Pyleus, and Stratius. Erginus avenged his father's death at the hands of the Thebans; he made war against Thebes, inflicting a heavy defeat. The Thebans were compelled to pay King Erginus a tribute of 100 oxen per year for twenty years. However, the tribute ended earlier than Erginus expected, when Heracles attacked the Minyan emissaries sent to exact the tribute. This prompted a second war between Orchomenus and Thebes, only this time Thebes (under the leadership of Heracles) was victorious, and a double tribute was imposed on the Orchomenians. Erginus was slain in battle according to the version of the story given by most ancient writers (e.g., the Bibliotheca, Strabo, Eustathius). But according to Pausanias, Erginus was spared by Heracles and lived to a ripe old age, and even fathered two sons (Trophonius and Agamedes) on a younger woman.