Lysander (died 395 B.C.), a Spartan naval and military commander. By defeating the Athenian fleet at Aegospotami in 405 B.C., and then capturing Athens in 404, Lysander ended the Peloponnesian War. For several years he was the most powerful man in Greece. He built a shortlived empire for Sparta by aiding local tyrants, who then paid him tribute. In Sparta, however, Lysander was unpopular, and his schemes to make himself ruler of the city were defeated. He was killed while leading a Spartan army in battle against the Boeotians.