The news came from the Franzen-Davis funeral home in Livingston, Montana.
No further details were given and messages left with Kidder's representatives were not immediately returned.
In a statement obtained by the news website, Miriam Kruger, executive director of Motor City Comic Con, said: "We are deeply saddened to hear of Margot Kidder's death".
Reeve died in 2004 after being paralyzed and confined to a wheelchair due to a horse riding accident in 1995. She became a household name after Superman was a massive box office hit in 1978.
By openly discussing her experiences with mental illness during a time when people, especially celebrities, didn't touch the subject, Kidder showed that anyone can have those struggles-and that it doesn't make them any less of a human being.
Kidder also starred in films like 1973's Sisters and 1979's The Amityville Horror.
The next year she worked with Robert Redford in The Great Waldo Pepper then with Peter Fonda in 92 In The Shade, making her a strong leading lady. Kidder recalled her childhood in northern Canada, saying, "We didn't have movies in this little mining town". Around that same time, her career had begun to decline, and she experienced a period of homelessness. They have a daughter, Maggie, and two grandchildren from Maggie's marriage to "Up in the Air" novelist Walter Kirn.
Kidder was eventually found by a homeowner in a back garden in Los Angeles, and was taken by the police to a local medical centre. She reprised the role in Superman II (1980), Superman III (1983) and Superman IV: The Quest for Peace (1987).
Margot Kidder's later movies were mostly of the horror genre, small independent films, or something with an indirect link to "Superman", but she proved her versatility as an actress by winning a Daytime Emmy Award in 2015.as a children's performer. She suffered from a famous breakdown in 1996, when she disappeared for several days.