Margot Kidder, best known for playing Lois Lane opposite Christopher Reeve in the classic Superman movies, has passed away at the age of 69. No cause of death was immediately given, though a Livingston, MT funeral home confirmed (via Deadline) Kidder’s passing, revealing that she died on Sunday, May 13.

Kidder’s career spanned numerous decades and included memorable roles in the Superman films of the late ’70s and ’80s, and The Amityville Horror. In her later years, following highly-publicized struggles with mental health, Kidder became a regular fixture on the convention circuit, happily signing autographs and posing for photos with fans.

Kidder was born on October 17, 1948, and began her acting career in the late ’60s. In 1968, she starred in her first major feature, Gaily, Gaily — a comedy co-starring Beau Bridges. Throughout the early ’70s, Kidder appeared on various TV shows, including the short-lived western Nichols, starring James Garner (with whom she later appeared in the controversial thriller The Glitter Dome). Kidder’s work in the ’70s and ’80s placed her opposite acclaimed actors like Robert Redford and Peter Fonda, though she’s become best known for playing Lois Lane in 1978’s Superman: The Movie; she reprised the role opposite Christopher Reeve in three more sequels. She remained close with Reeve until his death in 2004.

In addition to her iconic Superman role, Kidder was beloved for her roles in horror films, including Brian De Palma’s SistersThe Amityville Horror, and Black Christmas. Later in her career, Kidder became an outspoken advocate and activist for political and environmental causes.

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