Mary Louise Weller (born September 1, 1946) is an American actress. She is perhaps best known for her role as Mandy Pepperidge in the 1978 film Animal House. She has guest-starred in television series such as Starsky & Hutch, Fantasy Island, B.J. and the Bear, Supertrain, and CHiPs, as well as appeared in Larry Cohen's film Q.
Mary Louise Weller was born in New York City to Alexander L. Weller (1897-1979) and Annette Donay (1909-1990), and was raised in Los Angeles's Westwood area. She is of Lithuanian-Jewish descent. Danny Kaye was her godfather.
The onetime top New York model made her film debut with an uncredited role in the 1973 Al Pacino cop drama Serpico. In 1978, Weller starred as a marine biologist in the TV film Hunters of the Reef (1978) and then as Professor Andrew Prine's college-student lover in the horror film The Evil (1978). Her greatest renown is with her performance as prissy, uptight sorority sister Mandy Pepperidge in the 1978 hit comedy Animal House. After Animal House, Weller appeared in The Bell Jar (1979), Once Upon a Spy (1980), Forced Vengeance (1982), Blood Tide (1982), and Q (1982).
Weller acted in several plays in New York City and wrote the play Four Alone, which was performed at the Greenhouse Theater in Pasadena, California. She trained with the U.S. Equestrian Team as a teenager and has participated in horse-riding competitions.