The X Factor is a TV music competition with several international variants.

X Factor may also refer to:

• The X Factor (album), by Iron Maiden, 1995
• X-Factor (comics), a group of fictional mutant superheroes
• The X Factor, a 1965 book by Andre Norton
• "Ex-Factor", a 1998 song by Lauryn Hill

• Dante Hall (born 1978), nicknamed the X-factor, American footballer
• X-Factor (professional wrestling), a WWF wrestling stable
• X-Factor, or Sitout facebuster, a professional wrestling move

• X-factor (astrophysics), used to convert CO emission line brightness to molecular hydrogen mass
• X-factor, a gene mutation theory causing abnormally large hearts in horses

• Factor X (disambiguation)
• The Ex-Factor (disambiguation)
• Variable (mathematics)