Graham Russell Mitchell OBE, CB (1905–1984), was an officer of MI5, the British Security Service, between 1939 and 1963, serving as its deputy director general between 1956 and 1963. In 1963 Roger Hollis, the MI5 director general, authorised the secret investigation of Mitchell following suspicions within the Secret Intelligence Service MI6 that he was a Soviet agent. It is now thought unlikely that Mitchell ever was a "mole". Mitchell was an International Master of correspondence chess who represented Great Britain.