The term Men in Black (MIB), in popular culture, is used in UFO conspiracy theories to describe men dressed in black suits, sometimes with glowing eyes or other monstrous features, claiming to be government agents who attempt to harass or threaten UFO witnesses into silence. "All MIB are not necessarily garbed in dark suits," writes American writer Jerome Clark. "The term is a generic one, used to refer to any unusual, threatening or strangely behaved individual whose appearance on the scene can be linked in some fashion with a UFO sighting."

The phenomenon was initially and most frequently reported in the 1950s and 1960s; it is contemporaneous with many other conspiracy theories. The MIB supposedly intimidated a reporter in Pinewood, West Virginia to stop writing articles in newspapers about the MIB's presence in Pinewood. Pinewood was near the area where alleged sightings of a creature dubbed the Mothman were popular in the late 1960s, which make some people believe that the MIB are linked with the Mothman.

The term has also been adopted as a tongue-in-cheek term in geek culture for any generic suited government/corporate official. This usage has its roots in both the popularity of shows such as The X-Files and UFO culture, and the "threat" to hackers of Men in Black actually coming for them (in the form of the FBI or other cybercrime institutions).

The song "Men in Black" was recorded by rapper and actor Will Smith (also featuring singer Coko from double diamond selling group SWV) for the movie Men in Black, in which he also starred. The song plays during the movie's closing credits. Will Smith raps about how the MiBs "Walk in shadow, move in silence" and play the role of "first, last and only line of defence, against the worst scum of the universe." The song won Smith a Awards/Winners/Results.aspx?title=&winner=will+smith&year=0&genreID=0&hp=1" target="_blank">Grammy in 1997 for _Best Rap Solo Performance.

"Men In Black" features a sample of and a re-sung chorus from "Forget Me Nots" by Patrice Rushen. In a twist, the line "I want you to remember" is changed to "They won't let you remember", in reference to memory-erasing devices used in the Men in Black movie.

Aside from appearing on the movie's soundtrack, the song also appears on Will Smith's Columbia Records album Big Willie Style and reached #1 on charts in the UK, Australia and Germany. The song didn't chart on the Billboard Hot 100 because it was not released as a commercial single in the US; at the time, only songs that were commercially released as singles were eligible. It also reached #9 in the United World Chart. The music video for the song also appears on the DVD The Will Smith Collection. It was also included in the album All Time Greatest Movie Songs, released by Sony in 1999.