GRU
The GRU was well known in the Soviet government for its fierce independence from the rival "internal intelligence organizations", such as NKVD and KGB.  At the time of the GRU's creation, Lenin infuriated the Cheka (predecessor of the KGB) by ordering it not to interfere with the GRU's operations.  Nonetheless, the Cheka infiltrated the GRU in 1919.  This planted the seed for a fierce rivalry between the two agencies, which were both engaged in espionage. The rivalry was even more intense than that between the FBI and CIA.