Nicholas I may refer to:
Pope Nicholas I ( 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 ( 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 Nicholas I of Montenegro (1841–1921), King of Montenegro
See also
Niccolò I (disambiguation) Nicholas (disambiguation) Nikola I (disambiguation)