Dr. Alan L. Hart was an American physician, radiologist, tuberculosis researcher, writer and novelist. In 1917–18 Hart was one of the first to undergo gender affirmation surgery in the United States. Hart pioneered the use of x-ray photography in tuberculosis detection, and helped implement TB screening programs in the Pacific Northwest and Idaho. In 1948 Hart was appointed Director of Hospitalization and Rehabilitation for the Connecticut State Tuberculosis Commission. In addition to medical research, Hart wrote four popular fiction novels informed by his experience in the medical field: Doctor Mallory (1935), The Undaunted (1936), In the Lives of Men (1937), and Doctor Finlay Sees it Through (1942).

Hart was born October 4, 1890, in Halls Summit, Coffey County, Kansas, to Albert L. Hart and Edna Hart (née Bamford). When Hart's father died of typhoid fever in 1892, Hart's mother reverted to her maiden name and moved the family to Linn County, Oregon. In 1895 Hart's mother remarried, to Bill Barton. Hart attended Albany High School and Albany College, transferring to Stanford University in 1911-12. Hart earned a doctor of medicine degree from the University of Oregon Medical Department in 1917.

In 1917, Hart approached Joshua Allen Gilbert, Ph.D., M.D., at the University of Oregon who treated Hart both psychologically and medically. Hart's gender affirmation surgery was completed at the University of Oregon Medical School over the 1917–1918 winter vacation. Following the surgery Hart changed his name from Alberta Lucille to Alan. Hart's assigned name and sex designation remained unknown until Jonathan Ned Katz first identified Hart as the pseudonymous "H" in Joseph Gilbert's 1920s case notes. Katz featured Hart in his book, Gay American History: Lesbians and Gay Men in the U.S.A. (1976).

Hart was accomplished in the medical profession, and a popular writer of medical fiction. Hart was married to Inez Stark from 1918-1924, and to Edna Ruddick from 1925 until his death in 1962. Following his death, Edna Ruddick Hart establish a fund for research into leukemia, from which Hart's mother had died.