History Main / LetXBeTheUnknown

* "Project X" is a top secret government project in ''Literature/AtlasShrugged'', which turns out to be a horrifying [[FantasticNuke weapon of mass destruction]] based on [[MakeMeWannaShout certain frequencies of sound wave]]. The X officially stands for "Xylophone", but they're definitely playing up the mystery angle.

* There are at least three films called ''Project X'': one in [[http://en.wikipedia.org/wiki/Project_X_%281968_film%29 1968,]] on in 1987, and the [[Film/ProjectX 2012 comedy]].

** Mulder puts an X on the window to get in touch with his mysterious informant with no name or background (credited, appropriately, as Mr. X).

* In the ''Franchise/StarTrek'' franchise, experimental starships are given an "NX" designation until the spaceframe is approved for mass construction and an "NCC" registry.

* Science fiction/horror movie ''[[http://en.wikipedia.org/wiki/X_the_Unknown X the Unknown.]]''

* Ixpellia of the ''Franchise/LyricalNanoha'' franchise, also known as the then mysterious "[[SpellMyNameWithAnS X/Ix/Ikusu]]" that the Mariage was looking for during the case in ''Audioplay/StrikersSoundStageX''.

* ''VideoGame/HalfLife1: Opposing Force'' has its "Race X" aliens.

* "Generation X" was a term for disaffected, cynical youth that appeared as early as the post-war 1950s, but eventually became the specific demographic name for those born from roughly the early 1960s to the early 1980s. The adoption is credited to the 1991 novel ''Generation X: Tales for an Accelerated Culture'', which took the term from an earlier sociological book that defined "X" as a loose class of disaffected people who choose to stand apart from mainstream American society. It's probably not a coincidence that most of this generation also entered adulthood in UsefulNotes/TheNineties, the peak of XMakesAnythingCool.

* As with the games, before the second generation was fully revealed, the ''[[Anime/PokemonTheSeries Pokémon]]'' [[Anime/PokemonTheSeries anime]] used the CodeName "Pokémon X" for [[OlympusMons Lugia]]. Dr. Namba also refers to Lugia by this name, despite the episode that he debuts in having come out a while after the Generation 2 games were revealed. On a related note, ''Pokémon X''[[note]]The full title is ''Pokémon X: 10 Years of Pokémon''.[[/note]] is also the name of a CD album that was [[MilestoneCelebration released to commemorate the 10th anniversary]] of ''Franchise/{{Pokemon}}''.

* As with the games, before the second generation was fully revealed, the ''[[Anime/{{Pokemon}} Pokémon]]'' [[Anime/{{Pokemon}} anime]] used the CodeName "Pokémon X" for [[OlympusMons Lugia]]. Dr. Namba also refers to Lugia by this name, despite the episode that he debuts in having come out a while after the Generation 2 games were revealed. On a related note, ''Pokémon X''[[note]]The full title is ''Pokémon X: 10 Years of Pokémon''.[[/note]] is also the name of a CD album that was [[MilestoneCelebration released to commemorate the 10th anniversary]] of ''Franchise/{{Pokemon}}''.

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