Milton William Cooper (6 May 1943 - 5 November 2001), better known as Bill Cooper, was a radio host, author and political activist most known for his 1991 best-selling underground book Behold A Pale Horse, and his worldwide shortwave radio show Hour of the Time. Cooper was also well known for his court battle with the IRS and the recorded attempts to dissuade him from pursuing his case, as well as the related CAJI News Service brief titled BATF/IRS - Criminal Fraud where he alleges a history of crimes committed by the Internal Revenue Service, Bureau of Alcohol, Tobacco and Firearms and the Department of the Treasury. He had also produced several documentaries covering subjects such as the John F. Kennedy assassination and government "black projects". He was one of the first, if not the first, to suggest that Kennedy was murdered because he wanted to share UFO-related information with the Soviets. He also suggested that Marilyn Monroe was murdered because she had threatened to make UFO-related material public.
Throughout the late 1980s, Cooper was a controversial figure in the UFO research community. He followed many of the claims of John Lear: specifically, that the US government has had contact with and has entered into treaties with extraterrestrials which are, in fact, responsible for abductions. He circulated materials on Usenet as well as the old Paranet BBS, notable among them being a Petition to Indict those involved with the UFO cover-up. His UFO beliefs of the time are well described in Behold a Pale Horse.
Cooper was shot dead on November 5, 2001 during a gun battle outside his Arizona home with Sheriff's Deputies, at the age of 58.