The key revolutionary figure in the Russian Revolution of 1917 was Vladimir Lenin. As the leader of the Bolshevik Party, Lenin advocated for a proletarian uprising against the Tsarist regime. His return to Russia in April 1917, propelled by the German government, solidified his influence in the revolution. Lenin's leadership and ideologies led to the establishment of a socialist state and significantly influenced the trajectory of Marxist theory, fostering the conditions for the eventual founding of the Soviet Union and its global impact on communism.