'Animal House' Actress Mary Louise Weller Dead at 79

Actress Mary Louise Weller -- best known for her role as Mandy Pepperidge in the 1978 classic comedy film, "Animal House," is dead.

Mary died Thursday, one day before her birthday, after battling a brief illness ... her longtime boyfriend, Michael Roy Curtis, told The Hollywood Reporter.

The official cause of death is unclear.

Mary became famous for playing Pepperidge -- a stunningly beautiful, snobby college cheerleader -- opposite John Belushi, who played the infamous Bluto of Delta House -- a troubled fraternity at Faber College.

In perhaps the film's most iconic scene, Bluto climbs a ladder at Pepperidge's sorority house and peers through her window to watch her undress before tipping backwards and crashing to the ground. Despite their obvious differences, Bluto wins Pepperidge over in the end and drives into the sunset with her.

Mary also appeared in other movies such as "The Bell Jar" in 1979, and she was the love interest of Chuck Norris' character in the 1982 action thriller "Forced Vengeance."

In addition, Mary landed parts in several hit TV shows ... namely, "Baretta," "Kojak," "Starsky & Hutch," "Vegas," "Fantasy Island" and "CHiPs."

In 1986, Mary did a candid interview with the Los Angeles Times about her acting career ... saying, "I was the beautiful girl in trouble or the rich guy's daughter who owns a Porsche and won't give you the time of day."

Mary was also a top model back in the day in New York.

She was 79.