“Majestic 12 – in 1988, two FBI offices received similar versions of a memo titled “Operation Majestic-12…” claiming to be highly classified government document. The memo appeared to be a briefing for newly-elected President Eisenhower on a secret committee created to exploit a recovery of an extra-terrestrial aircraft and cover up this work from public examination. An Air Force investigation determined the document to be a fake.”

• From vault.fbi.gov 

Majestic 12, also known in short as MJ-12, is a purported organization that appears in many UFO conspiracy theories. The organization is claimed to be the code name of an alleged secret committee of scientists, military leaders, and government officials, formed in 1947 by an executive order by the U.S. President Harry S. Truman to facilitate recovery of an investigation of alien spacecraft. 

The concept originated in a series of supposedly leaked secret government documents first circulated by ufologists in 1984. Upon examination, the federal bureau of investigation (FBI) declared said documents to be “completely bogus”, and many ufologists consider them to be an elaborate hoax. 

Majestic 12 remains popular among some UFO conspiracy theorists and the concept has appeared in popular culture including television, film, and literature.