Ross Gunn (May 12, 1897 — October 15, 1966) was an American physicist, a key player in the USA nuclear submarine program, and a principal in the Manhattan Project.[1] The New York Times described Gunn as "one of the true fathers of the nuclear submarine program".[2] For his contributions to the Manhattan Project Gunn received the Navy Distinguished Civilian Service Award on September 4, 1945.[1][2] The National Academies Press said that he "was one of the most versatile physicists of the early and mid-twentieth century".[1] Gunn was a member of the National Academy of Sciences.[1] He also was a professor of physics at American University, the head of the Mechanics and Electricity Division, superintendent of the Aircraft Electrical Division, and technical director of the Army-Navy Precipitation Static Project, a technical adviser to the naval administration, director of the Weather Bureau's Physical Research Division.[1] Gunn was key in development of liquid thermal diffusion methods for separating of uranium isotopes for the Manhattan project.[1] He was also a fellow of the Institute of Radio Engineers.[1] Gunn held 45 patents.[2]