Cleonaeus () was a Rhodian admiral. He was second-in-command to Theophiliscus at the Battle of Chios, and he became commander after a victorious Theophilscius died from the wounds that he received during the battle. As Cleonaeus was sailing back to Rhodes, he was defeated by Philip V of Macedon at the Battle of Lade.
References
Polybius. The Rise of the Roman Empire.