Thomas Anthony Dooley III (January 17, 1927 – January 18, 1961) was an American physician who worked in Southeast Asia at the outset of American involvement in the Vietnam War. While serving as a physician in the United States Navy and afterwards, he became known for his humanitarian and anti-communist political activities up until his early death from cancer. After his death, the public learned that he had been recruited as an intelligence operative by the Central Intelligence Agency, and numerous descriptions of atrocities by the Viet Minh in his book Deliver Us From Evil had been fabricated.

Dooley has been called "a key agent in the first disinformation campaign of the Vietnam War," garnering support for the US government's growing involvement there. Dooley, one critic said, is an example of "celebrity sainthood" and the "intersection of show business and mysticism occupied the space where Tom Dooley was perhaps most at home"; nevertheless, he "helped to pull American Catholicism away from its insular, angry anti-Communism" and he lived a life that does not "invite facile judgment."

Dooley authored three popular books that described his activities in Vietnam and Laos: Deliver Us From Evil, The Edge of Tomorrow, and The Night They Burned the Mountain.

Dooley was born January 17, 1927, in St. Louis, Missouri, and raised in a prominent Roman Catholic Irish-American household. He attended St. Roch Catholic Elementary School and St. Louis University High School; at both he was a classmate of Michael Harrington. He then went to college at the University of Notre Dame, but completed only five semesters of course work. In 1944, he enlisted as a hospital corpsman in the United States Navy, serving in a naval hospital in New York City. In 1946, he returned to Notre Dame, but left without receiving a degree. Later, on June 5, 1960, Notre Dame presented him with an honorary degree. He entered the Saint Louis University School of Medicine. When he graduated in 1953, after repeating his final year of medical school, he joined the Navy. He completed his residency at Marine Corps Base Camp Pendleton, California, and then at Yokosuka, Japan. In 1954, he was assigned to the USS Montague, which was traveling to Vietnam.

In May 1954, the Geneva Agreements divided Vietnam at the 17th parallel north into two political zones. People north of the 17th parallel lived under the Viet Minh government, and those south of the 17th parallel lived under the government of Ngo Dinh Diem. Hanoi and Haiphong remained free zones until May 1955. In August 1954, Dooley transferred to Task Force Ninety, a unit participating in the evacuation of over 600,000 North Vietnamese known as Operation Passage to Freedom. Here he served as a French interpreter and medical officer for a Preventive Medicine Unit in Haiphong. He eventually oversaw the building and maintenance of refugee camps in Haiphong until May 1955, when the Viet Minh took over the city. He returned to Yokosuka, Japan in June 1955.

Dooley was assigned to the medical intelligence task force sponsored by the Military Advisory Assistance Group, whose leader, Lt. Gen. John W. O'Daniel, was an active ally of Ngo Dinh Diem. His official duties involved collecting samples for epidemiological work, "but his primary role was as a liaison between the refugee campaign...Operation Passage to Freedom and American reporters and politicians with an interest in Southeast Asia." In return for his work as a "spokesman", the doctor was awarded the highest presidential honor by Diem. During this period, he wrote numerous letters to his mother, many of which she shared with reporters; the letters were then printed in the local press, including the St. Louis Globe-Democrat. Most of the letters exaggerated his personal contribution to the refugee work. Despite his self-promotion, he "was indefatigable in taking care of his patients." Concerning the "self-aggrandizement" aspect of his personality, he said that to be a humanitarian in the modern world "you've gotta run it like a business. You've gotta have Madison Avenue, press relations, TV, radio...and of course you get condemned for being a publicity seeker;" he argued that being able to care for 100 people per day, between 1954 and 1958, with MEDICO later treating 2,000 per day, justified this approach to humanitarianism.

Dooley was soon recruited as an operative by Lieutenant Colonel Edward G. Lansdale, head of the CIA office in Saigon. He was chosen as a symbol of Vietnamese-American cooperation, and was encouraged to write about his experiences in the refugee camps. The CIA, USAID, and several other agencies "conducted fund-raising campaigns for the refugees" later described in his books. The Pentagon Papers would later note that he "significantly aided" in the gathering of intelligence information.

William Lederer, author of The Ugly American, helped initiate this phase of Dooley's career. Lederer, who was at the time serving as a Navy press officer attached to the admiralty, appreciated the eloquence of Dooley's situation reports, and suggested that he write a book. Immediately prior to publication, he and Lederer spent two weeks living together polishing the manuscript. Lederer was also on "special assignment" for the CIA during this period.