Vladimir Ilyich Ulyanov (22 April [O.S. 10 April] 1870 – 21 January 1924) was a Russian communist revolutionary, politician and political theorist. He served as head of government of the Russian Soviet Federative Socialist Republic from 1917, and of the Soviet Union from 1922 until his death. Under his administration, the Russian Empire was replaced by the Soviet Union; all wealth including land, industry and business was nationalized. Based in Marxism, his political theories are known as Leninism.
Born to a wealthy middle-class family in Simbirsk, Lenin gained an interest in revolutionary leftist politics following the execution of his brother Aleksandr in 1887. Expelled from Kazan State University for participating in anti-Tsarist protests, he devoted the following years to a law degree and to radical politics, becoming a Marxist. In 1893 he moved to St Petersburg, and became a senior figure in the Russian Social Democratic Labour Party (RSDLP). Arrested for sedition and exiled to Siberia for three years, he married Nadezhda Krupskaya, and fled to Western Europe, where he became known as a prominent party theorist. In 1903, he took a key role in the RSDLP schism, leading the Bolshevik faction against Julius Martov's Mensheviks. Briefly returning to Russia during the Revolution of 1905, he encouraged violent insurrection and later campaigned for the First World War to be transformed into a Europe-wide proletariat revolution. After the 1917 February Revolution ousted the Tsar, he returned to Russia.