The Great Purge or the Great Terror (Russian: Большо́й терро́р) was a campaign of political repression in the Soviet Union which occurred from 1936 to 1938. It involved a large-scale purge of the Communist Party and government officials, repression of peasants and the Red Army leadership, and widespread police surveillance, suspicion of "saboteurs", imprisonment, and arbitrary executions. In Russian historiography, the period of the most intense purge, 1937–1938, is called Yezhovshchina (Russian: Ежовщина; literally, "Yezhov phenomenon", commonly translated as "times of Yezhov" or "doings of Yezhov"), after Nikolai Yezhov, the head of the Soviet secret police, NKVD. It has been estimated between 600,000 and 3 million people died at the hands of the Soviet government during the Purge.
In the Western world, Robert Conquest's 1968 book The Great Terror popularized that phrase. Conquest's title was in turn an allusion to the period called the Reign of Terror (French: la Terreur, and, from June to July 1794, la Grande Terreur—the Great Terror) during the French Revolution.
The term "repression" was officially used to describe the prosecution of people considered counter-revolutionaries and enemies of the people by the leadership of the Soviet Union. The purge was motivated by the desire to remove dissenters from the Communist Party and to consolidate the authority of Joseph Stalin. Most public attention was focused on the purge of the leadership of the Communist Party, as well as of government bureaucrats and leaders of the armed forces, most of whom were Party members. The campaigns also affected many other categories of the society: intelligentsia, peasants and especially those branded as "too rich for a peasant" (kulaks), and professionals. A series of NKVD (the Soviet secret police) operations affected a number of national minorities, accused of being "fifth column" communities. A number of purges were officially explained as an elimination of the possibilities of sabotage and espionage, mostly by a fictitious "Polish Military Organisation" and, consequently, many victims of the purge were ordinary Soviet citizens of Polish origin.