Joseph Stalin was General Secretary of the Communist Party of the Soviet Union's Central Committee from 1922 until his death in 1953. During that time he established the regime now known as Stalinism. As one of several Central Committee Secretariats, Stalin's formal position was originally limited in scope, but he gradually consolidated power and became the de facto party leader and ruler of the Soviet Union.

Stalin launched a command economy in the Soviet Union, forced rapid industrialization of the largely rural country and collectivization of its agriculture. While the Soviet Union transformed from an agrarian economy to a major industrial powerhouse in a short span of time, millions of people died from hardships and famine that occurred as a result of the severe economic upheaval and party policies. At the end of 1930s, Stalin launched the Great Purges, a major campaign of repression against millions of people who were suspected of being a threat to the party were executed or exiled to Gulag labor camps in remote areas of Siberia or Central Asia. A number of ethnic groups in Russia were also forcibly resettled.

During Stalin's reign, the Soviet Union played a major role in the defeat of Nazi Germany in the Second World War (1939–1945) (more commonly known in Russia and post-Soviet republics as the Great Patriotic War). Under Stalin's leadership, the Soviet Union went on to achieve recognition as one of just two superpowers in the post-war era, a status that lasted for nearly four decades after his death until the dissolution of the Soviet Union.