In Greek mythology, Cycnus ( - "swan") was a cruel and bloodthirsty bandit. The son of Ares and Pelopia (or Pyrene), he seized control of the sacred grove of Apollo at Itonos in southern Thessaly, as he murdered pilgrims and stole offerings intended for the god. (Other sources say he dwelt by the river Echedorus in Macedonia). He faced off against Herakles in single combat, and ultimately lost despite the support he received from his father. He was afterwards transformed into a swan () and placed amongst the stars as the constellation Cygnus.