Joseph Stalin.

Iosif (Joseph) Vissarionovich Stalin, original name Ioseb Jughashvili was a Bolshevik revolutionary, and leader of the Soviet Union. Stalin became general secretary of the Soviet Communist Party in 1922; following the death of Vladimir Lenin, he prevailed over Leon Trotsky in a power struggle during the 1920s and fully consolidated his authority with the Great Purge, a period of severe repression which reached its peak in 1937, remaining in power through World War II and until his …

…of the 20th Party Congress of the Communist Party of the Soviet Union, Khrushchev denounced Stalin for his cult of personality and his regime for "violation of Leninist norms of legality". However, his immediate successors continued to follow the basic principles of Stalin's rule -- the political monopoly of the Communist Party presiding over a command economy and a security service able to suppress dissent. On the other hand the large-scale purges were never repeated.