Chronology of Soviet secret police agencies

There was a succession of Soviet secret police agencies over time. The first secret police after the October Revolution, created by Vladimir Lenin's decree on December 20, 1917, was called "Cheka" (ЧК). Officers were referred to as "chekists", a name that is still informally applied to people under the Federal Security Service of Russia, the KGB's successor in Russia after the dissolution of the Soviet Union.
For most agencies listed here secret policing operations were only part of their function; for instance, the KGB was both the secret police and the intelligence agency.
History of the Soviet state security organs.
Detailed chronology.
February 6, 1922: Cheka transforms into GPU, a department of the NKVD of the Russian SFSR.
November 15, 1923: GPU leaves the NKVD and becomes all-union OGPU under direct control of the Council of People's Commissars of the USSR.
July 10, 1934: NKVD of the Russian SFSR ceases to exist and transforms into the all-union NKVD of the USSR; OGPU becomes GUGB ("Main Directorate for State Security") in the all-union NKVD.
February 3, 1941: The GUGB of the NKVD was briefly separated out into the NKGB, then merged back in, and then on April 14, 1943 separated out again.
March 18, 1946: All People's Commissariats were renamed to Ministries.
The East German secret police, the Stasi, took their name from this iteration.
May 30, 1947: Official decision with the expressed purpose of "upgrading coordination of different intelligence services and concentrating their efforts on major directions". In the summer of 1948 the military personnel in KI were returned to the Soviet military to reconstitute foreign military intelligence service (GRU). KI sections dealing with the new East Bloc and Soviet émigrés were returned to the MGB in late 1948. In 1951 the KI returned to the MGB.
March 5, 1953: MVD and MGB are merged into the MVD by Lavrentiy Beria.
March 13, 1954: Newly independent force became the KGB, as Beria was purged and the MVD divested itself again of the functions of secret policing. After renamings and tumults, the KGB remained stable until 1991.
In 1991, after the State Emergency Committee failed to overthrow Gorbachev and Yeltsin took over, General Vadim Bakatin was given instructions to dissolve the KGB.
In Russia today, KGB functions are performed by the Foreign Intelligence Service (SVR), the Federal Counterintelligence Service which later became the Federal Security Service of the Russian Federation (FSB) in 1995, and the Federal Protective Service (FSO). The GRU continues to operate as well.