The KGB (anglicised to the Committee for State Security) was the intelligence body of the Soviet Union (Russia) in the latter half of the 20th century.
In the Julian Bashir, Secret Agent holoprogram, the character Colonel Anastasia Komananov was an operative of the KGB. (DS9: "Our Man Bashir")
The KGB ceased to exist when the Soviet Union dissolved in 1991. (VOY: "Future's End, Part I")