Ctesias (tē´shēəs, tē´sēəs), fl. 400 BC, Greek historian and physician of Cnidus. He lived many years in the Persian court. He tended Artaxerxes II when he was wounded in the battle of Cunaxa (401 BC). In 398 he was sent by the Persians as envoy to Evagoras and Conon. Of Ctesias' histories only Photius' abridgments of Persica and Indica remain; in them Ctesias hoped to show Herodotus' unreliability.