Nicholas I
Nicholas I may refer to:
- Pope Nicholas I, or Nicholas the Great
- Nicholas Mystikos, Patriarch Nicholas I of Constantinople
- Nicholas I (bishop of the Isles), Bishop-elect of the Isles
- Nicholas I, Lord of Mecklenburg
- Nicholas I of Transylvania, voivode of Transylvania
- Nicholas I (bishop of Schleswig)
- Patriarch Nicholas I of Alexandria, Greek Patriarch of Alexandria between 1210 and 1243
- Nicholas I, Duke of Troppau, natural son of king Ottokar II of Bohemia, became Duke of Troppau in Silesia
- Nicholas I, Lord of Rostock
- Nicholas I, Count of Tecklenburg
- Nicholas I Garai, chief governor of Bratislava, palatine to the King of Hungary
- Nicholas I of Opole
- Nicholas I, Duke of Lorraine
- Nicolaus I Bernoulli ; Swiss mathematician
- Nicholas I, Prince Esterházy, Hungarian prince
- Nicholas I of Russia, Emperor of Russia and King of Poland
- Nicholas I of Montenegro, King of Montenegro