David Ian Olive CBE FRS FLSW (/ˈɒlɪv/ ; 16 April 1937 – 7 November 2012) was a British theoretical physicist. Olive made fundamental contributions to string theory and duality theory, he is particularly known for his work on the GSO projection and Montonen–Olive duality. He was professor of physics at Imperial College, London, from 1984 to 1992. In 1992 he moved to Swansea University to help set up the new theoretical physics group.