Major Flemming Bruun Muus, DSO (born 21 November 1907, Copenhagen, Denmark – died 23 September 1982, Virum, Denmark) was a Danish author and resistance fighter during the German occupation of Denmark in the Second World War. In 1942, he was recruited in England by the Special Operations Executive and sent to Denmark in March 1943 as their chief agent. He was awarded the Distinguished Service Order for his contribution to the resistance movement and assistance with Denmark's liberation by the Allies. He was married to Varnika Wichfeld Muus who also contributed to the resistance movement.