Fritz Klein, Jr. (11 July 1924, Berlin – 26 May 2011, Berlin) was a German Marxist historian specializing in the German Empire and debates on the Empire's role before, during, and after World War II. He was an official East German historian prior to German reunification in 1990.[1] From 1979 to 1989, he served the Stasi as an informer under the codename "Wilhelm".[2]