Oleg Antonovich Gordievsky (Russian: Олег Антонович Гордиевский), CMG (born 10 October 1938 in Moscow, Russian SFSR, Soviet Union), is a former Colonel of the KGB and KGB Resident-designate (rezident) and bureau chief in London, who was a secret agent of the British Secret Intelligence Service (MI6) from 1974 to 1985.
Oleg Gordievsky attended the Moscow State Institute of International Relations, and on completion of his studies, joined the foreign service where he was posted to East Berlin in August 1961, just prior to completion of the Berlin Wall. He joined the KGB in 1963, and was posted to the Soviet embassy in Copenhagen, Denmark.
During his Danish posting, Gordievsky became disenchanted with his work in the KGB, particularly after the Soviet invasion of Czechoslovakia in 1968 – and made his sentiments known to MI6, who subsequently made contact with him. The value of MI6's recruitment of such a highly-placed and valuable intelligence asset increased dramatically when, in 1982, Gordievsky was assigned to the Soviet embassy in London as the KGB Resident-designate ("rezident"), responsible for Soviet intelligence gathering and espionage in the UK.