Donald Duart Maclean (; 25 May 1913 Marylebone, London – 6 March 1983 Moscow) was an English diplomat and member of the Cambridge Five who were members of MI5, MI6 or the diplomatic service who acted as spies for the Soviet Union in the Second World War and beyond. He was recruited as a "straight penetration agent" (not a double agent) while an undergraduate at Cambridge by the Soviet intelligence service. As a reward for his espionage activities, Maclean was brevetted as a colonel in the Soviet KGB.