Darius II, original name Ochus (died 404 BC), king of Persia (423-404 BC). He was an illegitimate son of Artaxerxes I, hence his Greek name, Nothos, meaning "bastard." As Ochus, he was a satrap of the province of Hyrcania when his father died. Ochus's half brother, Xerxes II, was king for a few weeks; another half brother, Sogdianus, murdered Xerxes II and was king for a few months; then Ochus murdered Sogdianus and ascended the throne, assuming the name of Darius.
In the early years of his reign the power of Athens prevented him from interfering in the affairs of Greece. But after Athens was defeated by Syracuse in 413 BC, Darius II intervened and supported Sparta for the remaining years of the Peloponnesian War. In 407 BC he sent his son Cyrus the Younger to command the combined Persian and Spartan forces in Asia Minor. Three years later he died. The 20 years of Darius's reign were notable primarily for ruthless suppression of a series of revolts within his empire.