Gary Heseltine is a British UFO researcher and retired police detective, known for collecting reports of UFO sightings by serving and retired police officers. Born in Scunthorpe, Lincolnshire, in 1960, he served in the Royal Air Force Police from 1983 to 1989 and then spent almost 24 years with the British Transport Police, 19 of them as a Home Office-trained detective constable, before retiring in 2013. His published biography says he worked as an advanced interviewer of witnesses and suspects.

In January 2002, while still serving, he launched the PRUFOS Police Database, short for Police Reporting UFO Sightings. It is an unofficial national archive of sightings that officers reported on and off duty, many of which, he says, involved more than one police witness. When the Western Daily Press profiled him in November 2003, he was a detective constable in Leeds and the collection held 84 sightings. He told the paper that "many officers are worried about saying anything in case it affects their jobs or careers." In a May 2026 interview he said the archive had grown to about 550 cases involving roughly 1,100 officers.

Heseltine also built a publishing career around the subject. After the death of UFO Magazine editor Graham Birdsall in 2003, he started the online magazine UFO Monthly, which his biography says ran for 41 issues between 2004 and 2007. He co-edited the print title UFO Data in 2008 and, after leaving the police in 2013, launched UFO Truth Magazine, a bi-monthly ezine. That April he spoke on behalf of police witnesses at the Citizen Hearing on Disclosure in Washington. In 2021 he became a co-founder and vice president of the International Coalition for Extraterrestrial Research.

His longest single project is the December 1980 Rendlesham Forest incident in Suffolk. In February 2023 he published NON-HUMAN: The Rendlesham Forest UFO Incidents: 42 Years of Denial, which he describes as the product of a five-year reinvestigation. In a February 2026 appearance on That UFO Podcast, he argued that the base's role as a nuclear weapons storage site is central to the case and discussed testimony describing light beams directed toward weapons bunkers. The Ministry of Defence has said the event posed no threat to national security and was never investigated as a security matter.

In December 2023 Heseltine founded UK Pilots Reporting UAP, a not-for-profit website that went live on 12 February 2024 and collects confidential reports from British pilots, air traffic controllers and radar operators, with a small volunteer team. He has said he concluded, on circumstantial grounds, that some UFOs are intelligently controlled and probably non-human in origin. His lasting contribution is the case files themselves: more than two decades of British police testimony, and now pilot reports, gathered and catalogued by a former detective.