She was the second Superman actor to work on the series Smallville, following in the footsteps of Christopher Reeve, who played Virgil Swann on the series. Margot's character was killed off the show after she refused to be the one who announced Swann's death, as she believed it was "distasteful" to do it so soon after Reeve's real-life death.
She is the aunt of actress Janet Kidder. They have worked together only once, on the episode Walk on By of the popular spy series La Femme Nikita. In the episode, Margot and Janet play older and younger versions of the same character.