Leonard H. Stringfield (1920–1994) was an American UFO researcher who, from the late 1970s, concentrated on stories of crashed flying saucers and recovered alien bodies in military custody. Over 16 years he produced seven Status Reports, most of them self-published and built largely on testimony from anonymous informants. For most of his career he also held a corporate job, retiring in 1981 as director of public relations and marketing services at DuBois Chemicals, a Cincinnati division of Chemed, after 31 years with the company.

Stringfield's UFO work began in the 1950s. From 1953 to 1957 he directed Civilian Research, Interplanetary Flying Objects (CRIFO), one of the larger civilian groups of the period, and published its newsletter, ORBIT. During those years, by his account, he reported sightings to the Air Defense Command in Columbus, Ohio, under a special code. He served as public relations adviser to the National Investigations Committee on Aerial Phenomena under Donald Keyhoe and later became director of public relations and a board member of MUFON. In the late 1960s he screened reports as an "early warning coordinator" for the University of Colorado project known as the Condon Committee. In 1977 Doubleday published his book Situation Red, the UFO Siege!, and in 1977–78 he advised Grenada's prime minister, Eric Gairy, on a proposed United Nations UFO research agency.

In July 1978 he presented Retrievals of the Third Kind, a case study of alleged UFOs and occupants in military custody, at the MUFON Symposium in Dayton. It later counted as the first Status Report, and six more followed through 1994. Their accounts, attributed to unnamed servicemen, doctors and scientists, described bodies delivered to Wright-Patterson Air Force Base, an alleged 1953 crash in Arizona and, in the 1982 report, two tall, pale, long-haired humanoid bodies. Stringfield also revived the Aztec, New Mexico crash story, which most ufologists had considered discredited since the 1950s, arguing that it was one of many craft the military had captured. He said some details had been entrusted to him on condition that they stay unpublished, and no document or physical material has confirmed his informants' central claims.

Stringfield passed away in December 1994, the year his seventh report, Search for Proof in a Hall of Mirrors, appeared. Interest in his files rose again after David Grusch told Congress in 2023 that the government was running a secret crash-retrieval program. When Grusch described alleged footage of pale, long-haired, human-looking beings in a new interview with Joe Rogan in 2026, commentators pointed to the similar bodies in Stringfield's 1982 report, while noting that the case was never verified. The researcher Richard Dolan devoted several 2026 videos to him, saying that Stringfield opened the field of crash-retrieval research and did more and better work on it than Stanton Friedman.

Stringfield's Status Reports remain the earliest large collection of crash-retrieval testimony in American ufology. Researchers still mine the cases he recorded, and his name returns whenever new claims about recovered craft and bodies surface, even though most of the people behind those cases were never publicly identified.