Peter the Great (Russian: , tr. Pyotr Velkiy, IPA: [ptr vlikj]), Peter I or Pyotr Aleksyevich (Russian: , IPA: [ptr lksejvt]; 9 June [O.S. 30 May] 1672 8 February [O.S. 28 January] 1725) was a monarch of the Tsardom of Russia and later the Russian Empire from 7 May [O.S. 27 April] 1682 until his death in 1725, jointly ruling before 1696 with his elder half-brother, Ivan V. Under his reign, Russia was modernised and grew into a European power.

Through a number of successful wars, he captured ports at Azov and the Baltic Sea, laying the groundwork for the Imperial Russian Navy, ending uncontested Swedish supremacy in the Baltic and beginning the Tsardom's expansion into a much larger empire that became a major European power. He led a cultural revolution that replaced some of the traditionalist and medieval social and political systems with ones that were modern, scientific, Westernised and based on the Enlightenment. Peter's reforms had a lasting impact on Russia, and many institutions of the Russian government trace their origins to his reign. He adopted the title of Emperor in place of the old title of Tsar in 1721, and founded and developed the city of Saint Petersburg, which remained the capital of Russia until 1918.

However, the formation of local elites domestically was not his main priority, and the first Russian universitySaint Petersburg State Universitywas founded only a year before his death, in 1724. The second one, Moscow State University, was founded 30 years after his death, during the reign of his daughter Elizabeth.

Tsar ( or ), also spelled czar, tzar, or csar, is a title used to designate East and South Slavic monarchs. In this last capacity it lends its name to a system of government, tsarist autocracy or tsarism. The term is derived from the Latin word caesar, which was intended to mean "emperor" in the European medieval sense of the term—a ruler with the same rank as a Roman emperor, holding it by the approval of another emperor or a supreme ecclesiastical official (the Pope or the Ecumenical Patriarch)—but was usually considered by western Europeans to be equivalent to "king"."Tsar" and its variants were the official titles of the following states:

Bulgarian Empire (First Bulgarian Empire in 919–1018, Second Bulgarian Empire in 1185–1396), and also used in Tsardom of Bulgaria, in 1908–1946

Serbian Empire, in 1346–1371

Tsardom of Russia, in 1547–1721 (replaced in 1721 by imperator in Russian Empire, but still remaining in use, also officially in relation to several regions until 1917)The first ruler to adopt the title tsar was Simeon I of Bulgaria. Simeon II, the last tsar of Bulgaria, is the last person to have borne the title tsar.