In American popular culture and UFO conspiracy theories, Men in Black (MIB) are men dressed in black suits who claim to be government agents who harass or threaten UFO witnesses to keep them quiet about what they have seen. It is sometimes implied that they may be aliens themselves. The term is also frequently used to describe mysterious men working for unknown organizations, as well as various branches of government allegedly designed to protect secrets or perform other strange activities. The term is generic, used for any unusual, threatening or strangely behaved individual whose appearance on the scene can be linked in some fashion with a UFO sighting.

Merlin is a legendary figure best known as the wizard featured in Arthurian legend. The standard depiction of the character first appears in Geoffrey of Monmouth's Historia Regum Britanniae, written c. 1136, and is based on an amalgamation of previous historical and legendary figures. Geoffrey combined existing stories of Myrddin Wyllt (Merlinus Caledonensis), a North Brythonic prophet and madman with no connection to King Arthur, with tales of the Romano-British war leader Ambrosius Aurelianus to form the composite figure he called Merlin Ambrosius (Welsh: Myrddin Emrys). Geoffrey's rendering of the character was immediately popular, especially in Wales. Later writers expanded the account to produce a fuller image of the wizard. Merlin's traditional biography casts him as a cambion: born of a mortal woman, sired by an incubus, the non-human wellspring from whom he inherits his supernatural powers and abilities. The name of Merlin's mother is not usually stated but is given as Adhan in the oldest version of the Prose Brut. Merlin matures to an ascendant sagehood and engineers the birth of Arthur through magic and intrigue. Later authors have Merlin serve as the king's advisor until he is bewitched and imprisoned by the Lady of the Lake.