Canadian-American actress Margot Kidder died in her sleep on Sunday at her Montana home, Varietyreported. She was 69. Kidder was best known for playing Lois Lane in the Superman films featuring Christopher Reeve.

Born in Canada in 1948, Kidder made her debut in Peter Pearson’s drama The Best Damn Fiddler from Calabogie to Kaladar (1968), where she played the eldest daughter of an itinerant bush worker. Her first major feature film was the American comedy Gaily Gaily (1969) opposite Beau Bronx.

Kidder gained recognition with Waris Hussein’s Quackser Fortune Has a Cousin in the Bronx (1970), in which she played an American exchange student who falls in love with a poor Irish horse manure collector (Gene Wilder). She went on to act in such films as Brian De Palma’s Sisters (1973) and The Great Waldo Pepper (1973), opposite Robert Redford.

Sisters (1973).

Kidder earned widespread fame when she played award-winning Daily Planet journalist Lois Lane in the iconic Superman (1978). A hard-nosed and witty professional, Lane is Superman’s love interest. Superman went on to become producer Warner Bros’ highest earner at that point and spawned three sequels: Superman II (1980), Superman III (1983), and Superman IV: The Quest for Peace (1987). Kidder reprised her role in all the sequels. Between the Superman films, she also worked on The Amityville Horror (1979).

Superman (1978).

Kidder continued to work in films through the 1980s and ’90s, appearing in productions like Heartaches (1981), The Glitter Dome (1984), and Showtime’s adaptation of Pygmalion (1983). Her career began to decline in 1990s and she was diagnosed with bipolar disorder after a much-publicised nervous breakdown in 1996. She went on to play smaller roles in television serials such as Smallville, Brothers and Sisters, and The L Word in the 2000s and also appeared in the off-Broadway production of The Vagina Monologues (2002). She won an Emmy award in 2015 for Outstanding Performer in Children’s Programming for RL Stine’s The Haunting Hour: The Series

Kidder married thrice. She had her only child, Maggie, in 1976 with novelist Thomas McGuane, whom she divorced in 1977. Kidder later married John Heard in 1979 for six days and French director Philippe de Broca in 1983. She divorced Broca a year later. Kidder has two grandchildren.

Several film industry members paid their tributes to the actress on Twitter.