Onesilus or Onesilos (Greek: Ὀνήσιλος, "useful one"; died 497 BC) was the brother of king Gorgos (Gorgus) of the Greek city-state of Salamis on the island of Cyprus.
Onesilos eller Onesilus (grekiska: Ονήσιλος), död 497 f.Kr., var bror till kung Gorgos (Gorgus) av den grekiska stadsstaten Salamis på ön Cypern.