Nicholas I

Nicholas I may refer to:

• Pope Nicholas I (c. 820 – 867), or Nicholas the Great
• Nicholas Mysticus, patriarch Nicholas I of Constantinople (852–925)
• Nicholas I of Transylvania, voivode of Transylvania (1201)
• Nicholas I, Bishop of Schleswig between 1209 and 1233
• 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 (c. 1255–1318)
• Nicholas I Garay (died 1386), chief governor of Bratislava, palatine to the King of Hungary
• Nicholas I of Opole (c. 1424 – 1476)
• Nicolaus I Bernoulli (1687–1759) in Basel; Swiss mathematician
• Nicholas I of Russia (r. 1825–1855), Tsar of Russia and King of Poland
• Nicholas I of Montenegro (1841–1921), king of Montenegro