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: