Clyde Tolson was born in Laredo, Missouri. He graduated from Laredo High School in 1915 and attended Cedar Rapids Business College from which he graduated in 1918. From 1919 to 1928, he was confidential secretary for three Secretaries of War: Newton D. Baker, John W. Weeks, and Dwight F. Davis. Tolson completed a Bachelor of Arts degree at George Washington University in 1925 and a law degree in 1927. While attending George Washington University, Tolson became a member of the Delta Pi Chapter of Sigma Nu Fraternity. In April 1928, Tolson applied to the FBI and was hired as a Special Agent later that month. Tolson reportedly indicated on his application that he wanted to use the job as a stepping stone to gain experience and earn enough money to open a law practice in Cedar Rapids. After working in the FBI’s Boston and Washington, D.C., field offices, he became the chief FBI clerk and was promoted to assistant director in 1930. In 1936, Clyde Tolson joined Hoover to arrest bank robber Alvin Karpis; later that year, survived a gunfight with gangster Harry Brunette. In 1942, Tolson participated in capturing Nazi saboteurs on Long Island and Florida. In 1947, he was made FBI Associate Director with duties in budget and administration. It has been stated that J. Edgar Hoover described Clyde Tolson as his alter ego: “They rode to and from work together, ate lunch together, traveled together on official business, and even vacationed together.” Rumors circulated for years that the two bachelors had a romantic relationship. Some authors dismissed the rumors about Hoover’s sexual orientation and possible intimate relationship with Tolson, while others have described them as probable or even “confirmed”, and still others reported the rumors without stating an opinion. When Hoover died, Tolson inherited his estate of US$551,000 and moved into his house; he accepted the U.S. flag draped on Hoover’s coffin.

In 1964, Clyde Tolson suffered a stroke, and, consequently, remained somewhat frail for the remainder of his life. In 1965, President Lyndon B. Johnson awarded him a gold medal for distinguished federal civilian service, saying Tolson “has been a vital force in raising the proficiency of law enforcement at all levels and in guiding the Federal Bureau of Investigation to new heights of accomplishment through periods of great National challenge.” Hoover kept Tolson employed in the FBI even after Tolson became too old for police duty and passed retirement age. After Hoover’s death on May 2, 1972, Tolson was briefly the acting head of the FBI. L. Patrick Gray became acting director on May 3. That same day, Tolson contacted Mark Felt and instructed him to write Tolson’s letter of resignation. Citing ill health, Tolson retired from the bureau on May 4, the day of Hoover’s funeral. Mark Felt was appointed to Tolson’s position. After Tolson’s departure from FBI, his health began to decline. On April 10, 1975, Tolson was admitted to Doctors Community Hospital in Washington, D.C. for renal failure. He died there four days later of heart failure at the age of 74. Tolson is buried in the Congressional Cemetery near J. Edgar Hoover’s grave.