Margot Kidder, who starred as Lois Lane in the 1978 Superman, dies in her sleep

Margot Kidder, who starred as Lois Lane opposite Christopher Reeve in the “Superman” film franchise of the 1970s and 1980s, has died.

Kidder died Sunday at her home in Livingston, Montana, according to a notice on the website of Franzen-Davis Funeral Home. She was 69. Kidder’s manager Camilla Fluxman Pines said she died peacefully in her sleep.

No cause or other details were given. “Superman,” directed by Richard Donner, was a superhero blockbuster two decades before comic book movies became the norm at the top of the box office, and is cited as an essential inspiration by makers of today’s Marvel and D.C. films. Both Kidder and Reeve, who played Superman, were relative unknowns when they got their leading parts in 1978′s “Superman.”

The filmmakers saved the star power for other roles — Gene Hackman as villain Lex Luthor and Marlon Brando as Reeve’s father Jor-El.

RIP Margot!