Leonard Monteath Thompson (born 6 March 1916, in Cranborne, Dorset, England - died June 2004) was Charles J. Stillé Professor of History Emeritus at Yale and director of the former Yale Southern African Research Program. He is well known for his work on the formation of the Union of South Africa and the two-volume The Oxford History of South Africa, a collaboration with N.M. Wilson., and has written and edited many books, including The Political Mythology of Apartheid, The Frontier in History (with Howard Lamar), A History of South Africa, and South African Politics (with Andrew Prior), all published by Yale University Press.