Vladimir Ilyich Ulyanov (better known by his alias Lenin) was a revolutionary, politician and political theorist. He helped organise the October Revolution in Russia in 1917, ending the Provisional Government, developing the ideas of Leninism and was the leader of the early USSR.
Widely considered one of the most significant and influential figures of the 20th century, Lenin was the posthumous subject of a pervasive personality cult within the Soviet Union until its dissolution in 1991. He became an ideological figurehead behind Marxism–Leninism and thus a prominent influence over the international communist movement. A controversial and highly divisive historical figure, Lenin is viewed by supporters as a champion of socialism and the working class, while critics on both the left and right emphasize his role as founder and leader of an authoritarian regime responsible for political repression and mass killings.