The Komityet Gosudarstvennoy Bezopasnosty (Russian Cyrillic Комитет государственной безопасности), literally the Committee for State Security, was the chief espionage agency of the Soviet Union from 1954 to 1991. The KGB was responsible for most espionage and counter-espionage activities, both foreign and domestic, essentially acting as a combined unit equal to the CIA and FBI in the United States, or a combination of MI5 and MI6 in the United Kingdom. Military intelligence was undertake by the GRU.
KGB agents appear in many Bond films; sometimes as allies, other times as enemies, but often as neutral parties. The KGB is first mentioned in From Russia with Love, where both Bond and SPECTRE are attempting to outwit the KGB agents protecting the Lektor Decoding Machine.
Despite having an initially uneasy relationship with Bond, ex-agent Valentin Zukovsky proved to be an extremely valuable ally on multiple occasions.
Both agent Max Zorin and assasin Victor Zokas deflected from the organization and would go on to make names for themselves in the outside world (Zorin establishes himself as a powerful industrialist while Zokas adopts the name Renard and becomes a terrorist). Both men were featured as the main antagonists of the Bond films A View to a Kill and The World Is Not Enough respectively.