The leader of the Bolsheviks was Vladimir Lenin. Lenin (1870-1924) was a Russian communist revolutionary, politician and political theorist. Ideologicaly, he was Marxist, and his political theories are called Leninism. Lenin played the main role in the October Revolution in 1917 overthrowing the Provisional Government. He established a one-party state under the new Communist Party. Lenin is widely considered as the one of the most significant and influential figures of the 20th century, and after his death he was the subject of a personality cult in Soviet Union.