Pi is a 1998 American psychological thriller film written and directed by Darren Aronofsky in his feature directorial debut. Pi was filmed on high-contrast black-and-white reversal film and earned Aronofsky the Directing Award at the 1998 Sundance Film Festival, the Independent Spirit Award for Best First Screenplay and the Gotham Open Palm Award.

The film explores themes of religion, mysticism, and the relationship of the universe to mathematics.

The story, about a mathematician with an obsession to find underlying complete order in the real world, contrasts two seemingly irreconcilable entities: the imperfect, irrational humanity and the rigor and regularity of mathematics, specifically number theory.