Casting Regan

Linda Blair will forever be synonymous with her role as Regan MacNeil, but the actress wasn't always going to play the possessed young girl.

Initially, Denise Nickerson – who played Violet Beauregarde in the Gene Wilder-starring 'Willy Wonka and the Chocolate Factory' – was up for the part, though the actress was eventually pulled from the shortlist after her parents read and were horrified by the horror movie's script.

As for Blair, it was her mother that put her forward for the role as the casting process was drawing to a close.

Director Friedkin recalled: "Linda came in at the very end, when we thought we couldn't make the film. Her mother brought her in to see me without an appointment. She was so well-adjusted. She was a straight-A student in Westport, Connecticut. And she was a totally together young girl."

Blair's mother was so determined to ensure he daughter landed the part that she hired tutors so that the actress didn’t fall behind at school while she worked on the film.