Nicholas I

Nicholas I may refer to:


 * Pope Nicholas I (c. 800–867), or Nicholas the Great
 * Nicholas Mystikos (852–925), Patriarch Nicholas I of Constantinople
 * Nicholas I (bishop of the Isles) (fl. 1147–1152), Bishop-elect of the Isles
 * Nicholas I, Lord of Mecklenburg (died 1200)
 * Nicholas I of Transylvania (died after 1203), voivode of Transylvania
 * Nicholas I (bishop of Schleswig) (died 1233)
 * Patriarch Nicholas I of Alexandria, Greek Patriarch of Alexandria between 1210 and 1243
 * Nicholas I, Duke of Troppau (c. 1255–1318), natural son of king Ottokar II of Bohemia, became Duke of Troppau in Silesia
 * Nicholas I, Lord of Rostock (died 1314)
 * Nicholas I, Count of Tecklenburg (died 1367)
 * Nicholas I Garai (died 1386), chief governor of Bratislava, palatine to the King of Hungary
 * Nicholas I of Opole (c. 1424–1476)
 * Nicholas I, Duke of Lorraine (1448–1473)
 * Nicolaus I Bernoulli (1687–1759); Swiss mathematician
 * Nicholas I, Prince Esterházy (1714–1790), Hungarian prince
 * Nicholas I of Russia (1796–1855), Emperor of Russia and King of Poland
 * Nikola I Petrović-Njegoš (1841–1921), King of Montenegro