Was the term "X-Files" invented by Mulder (in-universe)? Someone else at FBI before him?

  • 2
    fun fact: in the Fringe universe they referred to the FBI's "old X division cases".
    – KutuluMike
    Commented Nov 11, 2015 at 2:20
  • 9
    @MikeEdenfield fun fact: not all facts are fun.
    – Rand al'Thor
    Commented Nov 11, 2015 at 2:44
  • 3
    @randal'thor fun fact: not all fun facts claiming to disclaim fun facts are fun are fun, but that one was
    – Kroltan
    Commented Nov 11, 2015 at 11:51

1 Answer 1


There's an episode, Travelers (S5 E15), that explains where the term came from, and it stems from before Mulder's time. It was because the "U" file drawer was too full, for "unsolved" cases, but the "X" file drawer was virtually empty.

From then on, the mysterious cases were put in the X File.

Here's the transcript of the 1990 flashback scene where the name was explained by its creator:

BAHNSEN: I already checked. They're missing but I recognize one of these names. It's in an X-file.

DALES: An "X-file"?

BAHNSEN: Yes, unsolved cases. I file them under "x." (Goes to file cabinet..)

DALES: Why don't you file them under "u" for "unsolved"?

BAHNSEN: That's what I did until I ran out of room. Plenty of room in the "X"s.

  • 12
    I actually lol'd irl. That's the most awesome reason possible -- totally suitable for that particular story.
    – zxq9
    Commented Nov 11, 2015 at 10:57
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    It makes sense, then they're not sharing space with the large number of legitimate cases that could be filed under "u" for some name or location involved. What's not clear is why they've got a rigid alphabetic system instead of being able to have a drawer with a word on it.
    – Random832
    Commented Nov 11, 2015 at 14:11
  • That's a humorous justification. Commented Nov 11, 2015 at 20:53
  • I hate to be the Devil's advocate here, but what about letters V and W, as they come immediately after U ?
    – Sandun
    Commented Jul 8, 2021 at 13:52

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