King Nikola I Petrovic Njegos Краљ Никола I Петровић Његош (October 7, 1841- March 2, 1921) was the only king of Montenegro, reigning as a king from 1910 to 1918 and as a prince from 1860 to 1910.

Nikola became sovereign prince of Montenegro on the assassination of his uncle Danilo II in 1860. The country was embroiled in a series of wars with the Ottoman Empire between 1862 and 1878. However, the independence of Montenegro was recognised by all other countries at the Congress of Berlin in 1878 and in the succeeding decades Montenegro enjoyed considerable prosperity and stability. Education, communications and the army expanded greatly (the latter with support from Imperial Russia). Nikola gave Montenegro its first constitution in 1905 following pressure from a population eager for more freedom. He also introduced west-European style press freedom and criminal law codes.

The Montenegrin parliament declared Nikola king in 1910. After the First World War Montenegro united with the Kingdom of Serbia, as well as with other south Slav lands, to form the Kingdom of Serbs, Croats and Slovenes, which was renamed Yugoslavia in 1929.

Nikola went into exile in France 1918, but continued to claim the throne until his death three years later. He was buried in Italy. In 1989, the remains of Nikola, his queen Milena, and two of their twelve children were re-buried in Montenegro. One of his daughters, Anastasia, was married to the World War One general, Grand Duke Nicholas Nikolayevich of Russia. Another of Nikola and Milena’s children was Queen Elena of Italy, wife of King Victor Emmanuel III of Italy. Many of his daughters were married off to various princes and kings, giving Nikola the nickname "the father-in-law of Europe".