Peter John Farrelly (born December 17, 1956) is an American film director, screenwriter, producer and novelist. Along with his brother Bobby, the Farrelly brothers are best known for directing and producing quirky and romantic comedy films such as Dumb and Dumber, Shallow Hal, Me, Myself and Irene, There's Something About Mary, and the 2007 remake of The Heartbreak Kid.

Farrelly solo-directed and co-wrote the comedy-drama Green Book (2018), which won the Audience Award at the Toronto International Film Festival in 2018, the Golden Globe Award for Best Screenplay, and the Academy Awards for Best Picture and Best Original Screenplay.