Cleon (klē´ən), d. 422 BC, Athenian political leader. The son of a tanner, he had little education; nevertheless, he was a gifted speaker. He began his political career with a series of relentless attacks on Pericles. He was antagonistic to Sparta and successfully opposed (425 BC) Sparta's peace proposals. In the same year he was given command of the Athenian force blockading Sphacteria (an island at the mouth of the Bay of Pylos) and was brilliantly successful against the Spartans. Three years later he was given another command against the Spartans at Amphipolis, but he failed and was killed in action. His reputation as a vulgar and unprincipled demagogue is chiefly due to accounts by his enemies Thucydides and Aristophanes.