Kidder told CBS.
As Lois, Kidder was feisty and determined - a superhero in her own way. She was later placed in psychiatric care. "You've reached the goal, the thing that you said you wanted ... but also, it makes your life incredibly public", said Annie Kidder, who is based in Toronto. After a data-retrieval company failed to restore her lost work, Kidder became manic depressive, convinced that the federal government and her then-husband/novelist Thomas McGuane were plotting to kill her.
Actor Christopher Reeve as Superman (left) and as Clark Kent (right) with Lois Lane, played by Margot Kidder, in the 1978 film Superman: The Movie.
Margot Kidder dead: Superman actress who played Lois Lane dies aged 69
Park County Attorney Bruce Becker told TMZ police found her dead after a person of unknown identity called police to report that Margot was unconscious and wasn't breathing.
"I hope she's remembered as an advocate", her sister said.
Between Superman films she made 1979's blockbuster The Amityville Horror, 1981's Heartaches, 1983's Trenchcoat, 1984's The Glitter Dome, and 1985's Little Treasure. 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. She also appears alongside Christopher Reeve in one of the most famous scenes in cinema history.
In recent years though Kidder has been able to steadily work in independent film and television, including in roles on Smallville, The L Word, and in Rob Zombie's Halloween II (2009).
The Canadian-born actress was married and divorced three times.
After being reported missing for days in 1996, police took her away in handcuffs to Olive View-UCLA Medical Center. I'm grateful for the inspiring energy she brought to Lois & for her advocacy for #MentalHealthIsssues.
Kidder became an American citizen in 2005. The actress was married three times, first to novelist Thomas McGuane, in 1979 she Wednesday actor John Heard - but the couple split up six days after the wedding.
Margot Kidder, the Canadian-born actress who played Lois Lane in "Superman", has died. Something about her that feels whole and true.
Margot Kidder is one of Canada's greats.
"On-screen she was magic", he posted on Twitter.