Cyrus the Great (600?–529 B.C.), the founder of the ancient Persian Empire. He united the Persians, overthrew the Medes, and then conquered much of the Middle East. The empire he founded eventually extended from Libya to India.

Most of what we know of Cyrus' early life comes from the Greek historian Herodotus. According to Herodotus, Cyrus was a grandson of Astyage, king of the Medes. In 558 B.C. Cyrus became king of a realm that included Anshan and Persis, two Persian states then subject to the Medes. In 550 B.C. he overthrew Astyages and made himself king of the Medes and the Persians. He next invaded Asia Minor and attacked Lydia, which was ruled by Croesus. In 546 B.C. Cyrus' armies captured the Lydian capital of Sardis and overthrew Croesus. Babylon fell to his forces in 539 B.C. without battle.

Cyrus pursued a policy of religious toleration. He permitted the Jewish captives in Babylon, who had been taken by the Babylonians from their homeland in 586 B.C., to return to Judah. Cyrus died in 529 B.C., apparently as a result of wounds received in a war with a barbarian tribe. He was succeeded by his son Cambyses.

Cyrus is presented as the ideal ruler and general in the Cyropaediawritten by the Greek historian Xenophon.