a tyrant of Heraclea in Pontus, who was killed by Chion and Leonidas, Plato's pupils, during the celebration of the festivals of Bacchus. He had enjoyed the sovereign power during twelve years. Clearchus was also the name of a Macedonian who was sent to quiet the Byzantines, and being recalled, refused to obey, and fled to Cyrus the Younger, who made him captain of 13,000 Greek soldiers. He obtained a victory over Artaxerxes, who was so enraged at the defeat, that when Clearchus fell into his hands by the treachery of Tissaphernes, the king immediately put him to death.