The official title of Joseph Stalin was General Secretary of the Communist Party's Central Committee, according to PBS. Stalin ruled the Soviet Union for nearly three decades after Bolshevik Revolution leader Vladimir Lenin died in 1924.
While Stalin was never actually chosen to rule the Soviet Union, his position as the leader of the Communist Party allowed him to appoint individuals who supported him and eliminate enemies who opposed him. Stalin ruled the Soviet Union until his death in 1953. The practice of the Communist Party leader ruling the Soviet Union continued until after Mikhail Gorbachev left the position in 1991.