Simon Cowell's "The X Factor" is the latest TV program to use the mysterious, vaguely ominous-sounding 24th letter in its title. Here are five others:

The X-Files (1993-2002). Spooky series in which two stalwart FBI agents (David Duchovny, Gillian Anderson) searched for The Truth . . . which was out there.

The X Games (1995-). Annual summer and winter action sports competition created by ESPN.

The X Show (1999- 2001). Male-oriented late-night talk show on FX

XFL (2001). Short-lived, made-for-TV pro football league created by wrestling impresario Vince McMahon.

The X-Men (2011). The newest TV incarnation of the Marvel superheroes debuted this past Friday night on G4.

On the latest episode of "Sarra Sounds Off," Newsday's Gregg Sarra and Matt Lindsay take a look top boys and girls basketball players on Long Island. Credit: Newsday

Sarra Sounds Off, Ep. 15: LI's top basketball players On the latest episode of "Sarra Sounds Off," Newsday's Gregg Sarra and Matt Lindsay take a look top boys and girls basketball players on Long Island.

On the latest episode of "Sarra Sounds Off," Newsday's Gregg Sarra and Matt Lindsay take a look top boys and girls basketball players on Long Island. Credit: Newsday

Sarra Sounds Off, Ep. 15: LI's top basketball players On the latest episode of "Sarra Sounds Off," Newsday's Gregg Sarra and Matt Lindsay take a look top boys and girls basketball players on Long Island.

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