Ronald L. Nyswaner (born October 5, 1956) is an American screenwriter and film director. He has been nominated for numerous awards including a Academy Award, BAFTA Award, and a Primetime Emmy Award.

He is known for his screenplays Smithereens (1982), Philadelphia (1993), The Painted Veil (2006), Freeheld (2015), and My Policeman (2022). He is also known as a writer and producer of the Showtime series Ray Donovan (2013–2015) and Homeland (2017–2018).