Ivan, name of 6 Russian rulers. Ivan I (c. 1304–40) was grand prince of Moscow 1328–40. Ivan II (1326–59) was grand prince of Moscow 1353–59. Ivan III, Ivan the Great (1440–1505), was grand duke of Moscow 1462–1505. He paved the way for a unified Russia by annexing land, repelling the Tatars, strengthening central authority over the Church and nobility, and revising the law code. Ivan IV, Ivan the Terrible (1530–84), was grand prince from 1533 and the first tsar of Russia (1547–84). He annexed Siberia, consolidated control of the Volga River, and established diplomatic and trading relations with Europe. He strengthened the law and administration, but was notoriously cruel. Ivan V (1666–96) was co-tsar (with Peter I) 1682–90. Ivan VI (1740–64) was tsar 1740–41.