Epopeus was a mythical Greek King of Sicyon.

Zeus impregnated Antiope and she fled in shame (for she was married to Nycteus) to King Epopeus of Sicyon and abandoned her children, Amphion and Zethus. They were exposed on Mount Cithaeron , but were found and brought up by a shepherd. Nycteus, unable to retrieve his wife, sent his brother Lycus to take her. He did so and gave her as a slave to his own wife, Dirce.