Josef Stalin (born Iosef Besarionis dze Jughashvili – 18 December 1878 – 5 March 1953) was the General Secretary of the Communist Party of the Soviet Union's Central Committee from 1922 until his death in 1953. In the years following Lenin's death in 1924, he rose to become the leader of the Soviet Union.

Stalin launched a command economy, replacing the New Economic Policy of the 1920s with Five-Year Plans and launching a period of rapid industrialization and economic collectivization. The upheaval in the agricultural sector disrupted food production, resulting in widespread famine, such as the Soviet famine of 1932-1933, known in Ukraine as the Holodomor.

During the late 1930s, Stalin launched the (also known as the "Great Terror"), a campaign to purge of people accused of corruption or treachery; he extended it to the military and other sectors of Soviet society. Targets were often executed, imprisoned in Gulag labor camps or exiled. In the years following, millions of ethnic minorities were also deported.

In 1939, the Soviet Union under Stalin signed a non-aggression pact with Nazi Germany, followed by a Soviet invasion of Poland, Finland, the Baltics, Bessarabia and northern Bukovina. After Germany violated the pact in 1941, the Soviet Union joined the Allies to play a large role in the Axis defeat, at the cost of the largest death toll for any country in the war. Thereafter, contradicting statements at allied conferences, Stalin installed communist governments in most of Eastern Europe, forming the Eastern bloc, behind what was referred to as an "Iron Curtain" of Soviet rule. This launched the long period of antagonism known as the Cold War.

Stalin's careful control of the media helped him to foster a cult of personality. However, after his death his successor, Nikita Khrushchev, denounced his legacy, initiating the period known as de-Stalinization.