Margot Kidder, the vivacious actress who played Lois Lane opposite Christopher Reeve in the “Superman” movies and then waged a public battle with bipolar disorder, has died. She was 69.

Her manager, Camilla Fluxman Pines, said Kidman “died peacefully in her sleep Sunday” at her home in Livingston, Montana. She did not give the cause of death.

Margaret Ruth “Margot” Kidder, born in Yellowknife in the Northwest Territories of Canada in October 1948, was Canadian and American, actress and activist.

She started out in the 1960s in low-budget Canadian films and TV series, then hit the big time starring with Reeve in 1978 for her role as perky reporter Lois Lane in “Superman.” She also appeared in the three sequels. Later roles included “The Amityville Horror” in 1979.

She was aware from an early age, according to her diaries, that she suffered from constant mood swings, and even tried to kill herself as early as age 14. By the time she became a movie star she more and more sank into the throes of paranoia and what she would learn was bipolar disorder. 

One day, she disappeared and ended up living on the street as a homeless woman. A search was launched after she failed to board an airplane in 1996. Kidder eventually was found “dirty, frightened and paranoid,” hiding in the bushes of a Glendale, California, neighborhood, according to police. She was taken to a hospital for observation.

“If anything unfortunate happened to Margot, my heart goes out to her,” Reeve said in a statement at the time. “She is a dear friend who has always been there for me, and I would do anything to help her.” Reeve was later paralyzed in a riding accident and died in 2004.

Kidder later said her issues were rooted in manic depression. “It’s very hard to convince a manic person that there is anything wrong with them,” Kidder told People. “You have no desire to sleep. You are full of ideas.”

Kidder later started advocating for mental health wellness. In 2007, she said she had not had a manic episode in 11 years, and credited her health to alternative medicine through nutritional supplements.

She continued working, however. In 2015 she earned a Daytime Emmy Award as outstanding performer in a kids’ series for “R.L. Stine’s the Haunting Hour.”

“I don’t act much anymore unless I’m broke, and then I’ll take a job,” she told a Detroit radio station with a laugh.

She spent the last decades of her life living in Montana and engaging in political activism as a liberal Democrat, including protesting U.S. military action in Iraq.

Kidder is survived by a daughter, Maggie McGuane, with her first husband, American novelist Thomas McGuane, and two grandchildren from her daughter’s marriage to novelist Walter Kirn.

She was married to actor John Heard in 1979 for six days, and was married to French film director Philippe de Broca from 1983 to 1984.

A spokesman for the Franzen-Davis Funeral Home in Livingston, near Bozeman, Montana, said funeral arrangements for Kidder are pending.