The Roswell UFO incident in popular lore refers to the rumors and speculation regarding a July 1947 United States Army Air Forces balloon crash at a ranch near Roswell, New Mexico. Following local press interest in debris gathered from the crash site, and rumors that the debris came from a “flying disc”, the US military stated that the crashed object was merely a conventional weather balloon. Interest subsequently waned until the late 1970s, when ufologists began promoting a variety of increasingly elaborate conspiracy theories, claiming that one or more alien spacecraft had crash-landed and that the extraterrestrial occupants had been recovered by the military, which then engaged in a cover-up.

In the 1990s, the US military published two reports disclosing the true nature of the crashed object: a nuclear test surveillance balloon from Project Mogul. Nevertheless, the Roswell incident continues to be of interest in popular media, and conspiracy theories surrounding the event persist. Roswell has been described as “the world’s most famous, most exhaustively investigated, and most thoroughly debunked UFO claim”.