Friedrich Engels was a German social scientist, author, political theorist, philosopher, and father of Marxist theory, together with Karl Marx.
Karl Marx (5 May 1818 – 14 March 1883) was a German philosopher, economist, historian, political theorist, sociologist, journalist and revolutionary socialist.
Vladimir Ilyich Ulyanov, better known by the alias Lenin (22 April 1870-21 January 1924), was a Russian communist revolutionary, politician and political theorist. He served as head of government of Soviet Russia from 1917 to 1924 and of the Soviet Union from 1922 to 1924. Under his administration, Russia and then the wider Soviet Union became a one-party communist state governed by the Russian Communist Party. Ideologically a Marxist, he developed political theories known as Leninism.