Perhaps the most famous alien autopsy is supposed to have been performed on the body of an alien recovered from the crash of a “flying disk” near Roswell, New Mexico on June 2, 1947.
A 17-minute, black-and-white film of poor quality, purporting to be footage of the autopsy, surfaced in the 1990s, promoted by Ray Santilli, a London-based entrepreneur, who claimed he had received it from an unidentified, former military cameraman. The film was exposed as a hoax in 2006, when Santilli admitted the film was not in fact authentic, but a staged “reconstruction” of footage he claimed he had viewed in 1992, which had deteriorated and become unusable by the time he made his film. Santilli claimed that a few frames from the original were embedded in his film, but he never specified which ones. In 1995, before being exposed as a hoax, the film was sold to television networks and broadcast in more than 32 countries. [from Wikipedia]