Sir Howard Frank Trayton Smith, KCMG (15 October 1919 – 7 May 1996) was a British diplomat.

During World War II he worked at Bletchley Park, and later he became the British ambassador to Moscow. In 1979 he was unexpectedly appointed director general (DG) of MI5, the United Kingdom's internal security service, by James Callaghan, serving until 1981.