Clyde Anderson Tolson was the second-ranking official of the FBI from 1930 until 1972, from 1947 titled Associate Director, primarily responsible for personnel and discipline. He was the protégé and long-time top deputy of FBI Director J. Edgar Hoover.

John Edgar Hoover was an American law-enforcement administrator who served as the final Director of the Bureau of Investigation (BOI) and the first Director of the Federal Bureau of Investigation (FBI). President Calvin Coolidge first appointed Hoover as director of the BOI, the predecessor to the FBI, in 1924. After 11 years in the post, Hoover became instrumental in founding the FBI in June 1935, where he remained as director for an additional 37 years until his death in May 1972 – serving a total of 48 years leading both the BOI and the FBI and under eight Presidents.