(Πολύκλειτος), a physician of Messina in Sicily, to whom some of the epistles of Phalaris are addressed, and who, therefore (if he be a real personage), may be supposed to have lived in the sixth century B. C. Having cured the tyrant of a dangerous disease, he received from him some valuable presents, and also succeeded in persuading him to pardon a conspirator against his life (Phalar. Epist. 106, 109).