The Red Terror in Soviet Russia was a campaign of mass arrests, executions, and atrocities conducted by the Bolshevik government. In Soviet historiography, the Red Terror is described as having been officially announced on September 2, 1918 by Yakov Sverdlov and ended about October 1918. However, many historians, beginning with Sergei Melgunov, apply this term to political repression during the whole period of the Russian Civil War, 1918–1922. The mass repressions were conducted by the Cheka (the Bolshevik secret police), together with elements of the Bolshevik military intelligence agency (the GRU).

The term "Red Terror" was originally used to describe the last six weeks of the "Reign of Terror" of the French Revolution, ending on July 28, 1794 with the execution of Maximilien Robespierre, to distinguish it from the subsequent First White Terror. (historically this period has been known as the Great Terror (French: la Grande Terreur)

The Red Terror was presented by the Bolsheviks as a response to White Terror. The stated purpose of the Terror was to eliminate counter-revolutionaries who belonged to former "ruling classes". Martin Latsis, chief of the Ukrainian Cheka, explained in the newspaper Red Terror:

Joseph Vissarionovich Stalin (Russian: Иосиф Виссарионович Сталин; born Iosif Vissarionovich Dzhugashvili, Russian: Иосиф Виссарионович Джугашвили; 18 December 1878 – 5 March 1953) was the Premier of the Soviet Union from 6 May 1941 to 5 March 1953. He was among the Bolshevik revolutionaries who brought about the October Revolution in Russia in 1917 and later held the position of General Secretary of the Communist Party of the Soviet Union's Central Committee from 1922 until his death in 1953. While the office of the General Secretary was officially elective and not initially regarded as the top position in the Soviet state, Stalin managed to use it to consolidate more and more power in his hands after the death of Vladimir Lenin in 1924 and gradually put down all opposition groups within the Communist Party. This included Leon Trotsky, a socialist theorist and the principal critic of Stalin among the early Soviet leaders, who was exiled from the Soviet Union in 1929. Whereas Trotsky was an exponent of permanent revolution, it was Stalin's concept of socialism in one country that became the primary focus of Soviet politics.