In Greek mythology, Eurypylus (Ancient Greek Εὐρύπυλος, "wide-gated") was a king of the island of Cos, son of Poseidon by Astypalaea (or Mestra). Homer names him in connection with the isle's chief city; Apollodorus has Heracles kill him when the Coans mistake the hero for a pirate — or, in another version, when Heracles storms Cos for Eurypylus' daughter Chalciope.
Adapted from Wikipedia, "Eurypylus of Cos" · CC BY-SA 4.0
I.King of Cos
Eurypylus ruled Cos as son of Poseidon and Astypalaea, or of Poseidon and Mestra in the Hesiodic Catalogue. He was husband of Clytie and father of Chalciope, Chalcon, and Antagoras. Homer alludes to him in the island's royal geography; later mythographers fill out the Poseidonian genealogy.
II.Death at Heracles' hands
When Heracles landed on Cos to escape a storm sent by Hera, the Coans took him for a pirate and attacked; in the battle Eurypylus was killed. Another version has Heracles plan the assault because he desired Chalciope, who became mother of Heracles' son Thessalus. Apollodorus (2.7.1, 2.7.8) is the chief continuous summary.
III.Homonyms
This atlas entry (eurypylus-cos) is the Coan son of Poseidon. Distinct from Eurypylus son of Euaemon, the Thessalian Achaean at Troy (eurypylus-euaemonid); from Eurypylus son of Telephus, the Mysian ally of Troy (eurypylus-telephus); and from lesser namesakes (Thespiad, suitor, Temenid, and others).