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

She achieved success as a child actress, and received a nomination for an Academy Award for Best Supporting Actress for her performance in The Bad Seed (1956). Her acting career has continued with supporting roles in film and television, including a more recent performance as Pat Nixon in Frost/Nixon (2008).

McCormack was born Patricia Ellen Russo in Brooklyn, New York, the daughter of Elizabeth (née McCormack), a professional roller skater, and Frank Russo, a fireman. She was a child model at the age of four and began appearing on television at the age of seven. She made her motion picture debut in Two Gals and a Guy (1951) and appeared in the television series Mama from 1953 to 1956.