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 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 have emphasised his role as founder and leader of an authoritarian regime responsible for political repression and mass killings.