Otto I (disambiguation)

• Otto I, Duke of Saxony or Otto the Illustrious
• Otto I, Count of Chiny
• Otto I, Duke of Carinthia or Otto of Worms
• Otto I, Duke of Swabia and Bavaria
• Otto I, Marquess of Montferrat
• Otto I, Count of Savoy
• Otto I, Count of Duras
• Otto I, Margrave of Meissen
• Otto I, Count of Scheyern
• Otto I, Count of Scheyern-Dachau-Valley
• Otto I, Count of Salm, co-ruler of the County Palatine of the Rhine
• Otto I
• Otto I, Duke of Bavaria or Otto the Redhead
• Otto I, Margrave of Brandenburg
• Otto I, Count of Guelders and Zutphen
• Otto I, Count of Burgundy, Count of Luxembourg
• Otto I, Duke of Merania
• Otto I or Otto van Gelre
• Otto I, Count of Oldenburg
• Otto I, Duke of Brunswick-Lüneburg or Otto the Child
• Otto I, Count of Nassau
• Otto I, Prince of Anhalt-Aschersleben
• Otto I, Landgrave of Hesse
• Otto I, Duke of Pomerania, Duke of Stettin
• Otto I, Count of Schwerin
• Otto I, Margrave of Hachberg-Sausenberg, also Margrave of Rötteln
• Otto I, Duke of Brunswick-Göttingen or Otto the Evil
• Otto I, Count Palatine of Mosbach
• Otto I, Duke of Brunswick-Harburg, Prince of Lüneburg
• Otto I of Greece
• Otto, King of Bavaria
• Otto I of Austria or Otto von Habsburg, Crown Prince of Austria-Hungary