The daughter of a mining engineer, Canadian actress Margot Kidder spent her first two-and-a-half years living in a caboose. While attending the University of British Columbia, Kidder was talked into appearing in a college stage production of Take Me Along; she was hooked, though she later learned there was more to acting than crying on cue and partying. In her first professional years with the Canadian Broadcasting Corporation headquarters in Vancouver, Kidder played everything from simpering ingenues to an unhinged murderess. She made her first film in 1969, an American production titled Gaily Gaily, then worked with Gene Wilder in the British-made Quackser Fortune Has a Cousin in the Bronx (1970). Kidder disliked the seamier side of the movie business and retreated to Canada in hopes of learning how to become a film editor, but was brought back to the U.S. in 1971 for a continuing role in the James Garner TV series Nichols. She liked Garner but not the hassles of making a weekly series, and for the next decade concentrated on film work, plunging headfirst into a kinky Brian DePalma chiller titled Sisters (1972). Kidder's best-known work in the '70s and '80s was as Lois Lane in the Superman films starring Christopher Reeve. Other movie roles and a stint on 1987 TV series Shell Game followed. She continued to work steadily in a variety of projects including 1988's Body of Evidence, White Room, and Hanry & Verlin, however she earned the most press she had in quite some time after a bizarre incident in 1996 where she went missing for a few days and was found dazed and confused outside a stranger's home in Glendale, California. She recovered and went back to work in numerous films and TV series including Touched By an Angel and Tribulation. She was a major figure in Peter Biskind's book about '70s cinema, Easy Riders, Raging Bulls, and figured prominently in the documentary made from that book.
In 2007 she appeared on the reality program Who Do You Think You Are, and went on to act in Rob Zombie's remake of Halloween II.
Kidder married and divorced writer Tom McGuane and actor John Heard (their union lasted six days!) and remains a vocal activist for political and ecological causes.