Otto III, Holy Roman Emperor (980–1002) was Holy Roman Emperor from 996 until his death.
Otto III may also refer to:
Otto III, Duke of Swabia (died 1057) Otto III, Count Palatine of Burgundy (1208–1248) Otto III, Margrave of Brandenburg (1215–1267) Otto III, Count of Weimar-Orlamünde (1244–1285) Otto III, Duke of Bavaria (1261–1312) Otto III of Carinthia (c. 1265–1310) Otto III, Marquess of Montferrat (died 1378) Otto III, Prince of Anhalt-Bernburg (died 1404) Otto III, Count of Waldeck (c. 1389–1458/9) Otto III, Duke of Pomerania (1444–1464) Otto III, Count of Rietberg (between 1475 and 1485–1535)
See also Otto I (disambiguation) Otto II (disambiguation) Otto IV (disambiguation) Otto V (disambiguation) Otto VI (disambiguation) Otto VII (disambiguation) Otto VIII (disambiguation)