Athan George Theoharis (August 3, 1936 – July 3, 2021) was an American historian, professor of history at Marquette University in Milwaukee, Wisconsin.
As well as his extensive teaching career, he was noteworthy as an expert on the Federal Bureau of Investigation (FBI), J. Edgar Hoover, and U.S. intelligence agencies, having written and edited many books on these and related subjects.
[1][2] At the time of his death, the Milwaukee Sentinel Journal called him a "persistent scourge of the FBI" due to its violations of American civil liberties.
[2] Theoharis's first book was Anatomy of Anti-Communism (1969), which was quickly followed with the publication of his revised PhD dissertation, directed under the supervision of Walter Johnson, titled The Yalta Myths: An Issue in U.S.
[5] In 1975, because of his work exploring the Truman and Eisenhower loyalty and security programs as well as his articles on FBI wiretapping, Theoharis was asked by the Church Committee to conduct research at presidential libraries.