Patricia "Patty" McCormack (born Patricia Ellen Russo; August 21, 1945) is an American actress with a career in theater, films, and television.

McCormack began her career as a child actress. She is perhaps best known for her performance as Rhoda Penmark in Maxwell Anderson's 1956 psychological drama The Bad Seed. She received critical acclaim for the role on Broadway and was nominated for an Academy Award for Best Supporting Actress for her performance in Mervyn LeRoy's film adaptation of the same name in 1956. Her acting career has continued with both starring and supporting roles in film and television, including Helen Keller in the original Playhouse 90 production of The Miracle Worker, Jeffrey Tambor's wife Anne Brookes on the ABC sitcom The Ropers, and a more recent performance as Pat Nixon in Frost/Nixon (2008).