William Leonard Langer was an American historian, intelligence analyst and policy advisor. He served as chairman of the history department at Harvard University. He was on leave during World War II as head of the Research and Analysis Branch of the Office of Strategic Services. He was a specialist on the diplomacy of the periods 1840–1900 and World War II. He edited many books, including a series on European history, a large-scale reference book, and a university textbook.

Walter Charles Langer was an American psychoanalyst who prepared a detailed psychological analysis of Adolf Hitler in 1943. Langer studied psychoanalysis at Harvard University, where he worked as a professor upon completion of his education. Langer was later employed by the Office of Strategic Services (OSS), where in 1943 he prepared a psychoanalysis profile of Hitler. In this analysis, Langer accurately predicted that Hitler would commit suicide as the "most plausible outcome", and the possibility of a military coup against Hitler well before the assassination attempt of 1944.