Leopold Henri Haimson (1927 – December 18, 2010) was a historian and professor emeritus of Columbia University.
Haimson received his PhD from Harvard University in history and social relations in 1952. He was a member of faculty at the University of Chicago from 1956. He joined the faculty at Columbia in 1965 as a professor of Russian history and a member of the Russian Institute. He has been the Director of the Interuniversity Project on the History of Menshevik Movement and a Fellow at the Center for Advanced Study in the Behavioral Sciences at Stanford University. He published many books and articles, specializing in the history of Russia, particularly the Mensheviks movement.