A king of Colonae with this name was an invulnerable son of Poseidon who was strangled by Achilles with the straps of his own helmet, after which his spirit was turned into a bird.
After Ceyx buried a figure with this name, the headstone was washed away when a river flooded at Apollo's command. A man with this name had Phylius capture man-eating birds, wrestle a bull, and strangle a lion in order to prove his love. According to Apollodorus and Hyginus, a thunderbolt kept Heracles and Ares from fighting each other after Heracles killed a son of Ares with this name. That story is the subject of the poem Shield of Heracles. The best-known figure with this name had a musician named Molpus stoned to death and Philonome buried alive after the two conspired to have his son Tenes exiled. Another figure with this name wept by the Eridanos River after his close friend (*) Phaethon was killed. A king of Colonae with this name was an invulnerable son of Poseidon who was strangled by Achilles with the straps of his own helmet, after which his spirit was turned into a bird. For 10 points, give this Greek name held by various people who turned into swans. 
After Ceyx buried a figure with this name, the headstone was washed away when a river flooded at Apollo's command.
Cycnus [or  Cygnus; or  Kyknos]