Margot Kidder, famous for portraying Lois Lane in “Superman,” died Sunday in Montana.

Margot was at her home when she passed away, according to the spokesperson at Franzen-Davis Funeral Home in Livingston, MT. The cause of death is currently still unknown.

Local Police were called to report that Margot was found unconscious and not breathing. Police responded and found her dead. The Livingston Police Chief says foul play is not considered a factor, but her death is currently under investigation.

Margot starred opposite Christopher Reeve in the original 1978 Superman movie, as well as in the 3 sequels that followed. She continued acting right up until this year, taking small roles in TV shows, movies and stage roles.

She battled bipolar disorder for a number of years and struggled with briefly being homeless in 1996. Not long after that she became an advocate for mental health.

She had been married 3 times, but was single at the time of her death.

Margot Kidder is survived by a daughter.