John Wallis (November 23, 1616 – October 28, 1703) is an English mathematician who is given partial credit for the development of infinitesimal calculus.

Between 1643 and 1689,he serves as chief cryptographer for Parliament and, later, the royal court.

He is also credited with introducing the symbol ∞ for infinity.

He similarly uses \frac{1}{\infty} for an infinitesimal.

Asteroid 31982 Johnwallis is named after him.