Leopold Henri Haimson (1927 – December 18, 2010) was a Belgian-born American historian whose work focused on the history of the Soviet Union.
Haimson was born in Brussels to Russian émigré parents.
In 1940, fleeing the Nazi invasion, the Haimson family escaped first to France and then to the United States, where they would settle.
He was 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.