Margot Kidder passed away on Sunday at her home in Livingston, Montana, PEOPLE has confirmed. She was 69. Her cause of death is unknown.
Funeral arrangements for the Canadian-born actress are pending.
Kidder began acting in the late 1960s, but rose to fame in 1978 for her role as Lois Lane in Superman: The Movie opposite Christopher Reeve. She went on to reprise the part in the movie’s three sequels.
She also starred as Kathy Lutz in The Amityville Horror (1979), and appeared in movies such as Black Christmas (1974) and Heartaches (1981). Kidder acted as producer and starred as Eliza Doolittle in a 1983 adaptation of Pygmalion with Peter O’Toole for Showtime.
Despite her success, Kidder battled mental health issues that left her homeless.
After being reported missing for days in 1996, police took her away in handcuffs to Olive View-UCLA Medical Center.
“The woman we saw was in obvious mental distress,” Officer Rick Young of the Glendale police told PEOPLE at the time. “She didn’t think one person was following her. She thought a whole group of people were after her.”
Kidder told PEOPLE five months later that the root of most of her problems — which include “mood swings that could knock over a building” — was manic depression. She was first diagnosed with the condition by an L.A. psychiatrist eight years prior, but she refused to take the recommended prescription of lithium, the recommended treatment.
“It’s very hard to convince a manic person that there is anything wrong with them,” said Kidder, who was working on a memoir at the time. “You have no desire to sleep. You are full of ideas.”
She is survived by her daughter, Maggie McGuane.