John IV

John IV may refer to:

• Patriarch John IV of Constantinople, Patriarch from 582 to his death in 595
• Pope John IV, Pope from 640 to his death in 642
• John IV, Bishop of Naples (died 835)
• John IV of Naples, Duke from 997 to after 1002
• John IV of Gaeta (died 1012)
• John IV Laskaris (1250–c. 1305), Emperor of Nicaea from 1259 to 1261
• John IV, Duke of Brittany (1295–1345)
• John IV, Duke of Brabant (1403–1427)
• John IV, Duke of Mecklenburg (1370–1422)
• John IV of Trebizond (c. 1403–1459)
• John IV, Duke of Bavaria (1437–1463)
• Ivan IV of Russia (Ivan the Terrible, 1530–1584)
• John IV of Portugal (1603–1656), known as John II, Duke of Braganza, before 1640
• John IV of Ethiopia (c. 1831–1889)