Nicolas Fatio de Duillier (alternative names are Facio or Faccio) (26 February 1664 – 12 May 1753) is a Swiss mathematician known for his work on the zodiacal light problem, for his very close relationship with Isaac Newton, for his role in the Newton v. Leibniz calculus controversy, and for originating the "push" or "shadow" theory of gravitation.

He also develops and patents a method of perforating jewels for use in clocks.