Joseph Stalin's secret police was named the People's Comissariat for Internal Affairs. Its name took the abbreviation of NKVD in Russian, and it was formed in 1934.
The first secret police in Russia was known as the Cheka and was use primarily by the Bolsheviks to further their political agenda. However, once the Russian Civil War ended, the Cheka was disbanded. Its functions were transferred to State Political Directorate, or GPU. The GPU was at first less powerful than the Cheka; however, once Joseph Stalin entered power, he renamed the group the NKVD and reestablished its power, specifically its punitive power. The police exercising power in this way led to this period of time being referred to as the Great Terror of the 1930s.