Mary Louise Wilson (born November 12, 1931) is an American actress, singer, and comedian. In a career that has spanned more than 50 years, she has appeared in numerous plays, films and television shows. In film, notable credits include Klute (1971), The Best Little Whorehouse in Texas (1982), Teachers (1984), The Money Pit (1986), Pet Sematary (1989), Green Card (1990), Stepmom (1998), Nebraska (2013), and Ocean's Eight (2018). Wilson has appeared in many television series such as Maude, Lou Grant, Remember WENN, Frasier, The Sopranos, Nurse Jackie, Mozart in the Jungle, Modern Family, and Orange Is the New Black, usually in guest roles.

Wilson has had scores of stage roles, making her Broadway debut in Hot Spot (1963) starring Judy Holliday. For her role as "Big" Edie Beale in the musical Grey Gardens (2006), Wilson won the Tony Award for Best Performance by a Featured Actress in a Musical (alongside co-star Christine Ebersole's win for Best Leading actress). She was previously nominated in the same category for her role as Fräulein Schneider in the 1998 revival of Cabaret.