Das Doppelleben eines Diktators; literally "Hitler's Secret: The Double Life of a Dictator") is a 2001 book by German professor and historian Lothar Machtan.

Among the evidence, he cites the allegedly homoerotic nature of his friendship with August Kubizek during Hitler's youth in Vienna.

The book was not well received by historians, who dispute Machtan's conclusion that Hitler was homosexual.

report from the J. Edgar Hoover era rather than an evenhanded work of scholarship in which the author is ready to be led by the facts.

To interpret evidence his way, Machtan employs innuendo and insinuation ..." However, the review, written by Walter Reich, a psychiatrist and former director of the United States Holocaust Memorial Museum, also concedes that "though Machtan doesn't succeed in proving that Hitler was an active homosexual, he does demonstrate that his life, in both the personal and the political spheres, was suffused with homosexual themes and personalities.