10 Actors Who Were Uncredited For Insane Reasons
7. To Increase Linda Blair's Chances Of Winning An Oscar - Mercedes McCambridge (The Exorcist)
Despite being an Oscar-winning actress and having been dubbed "the world's greatest living radio actress" by none other than Orson Welles, Mercedes McCambridge wasn't originally credited for her work on The Exorcist, where she voiced the demon Pazuzu who possesses young Regan (Linda Blair).
Early release prints of the film didn't include McCambridge's name, a fact which reportedly left McCambridge understandably incensed at the film's premiere, prompting her to initiate arbitration proceedings against Warner Bros. with the Screen Actors Guild (SAG).
It's been suggested many times over the years that Warner Bros. didn't want either McCambridge or Eileen Dietz - who played the face of Pazuzu and acted as a stand-in for Blair in several challenging scenes - being credited for fear that it might diminish Blair's chance of receiving a Best Supporting Actress Oscar nomination.
Ultimately SAG ruled in favour of McCambridge, ensuring that her name was added to all future prints of the film, and Blair went on to receive an Oscar nomination regardless.
Some continue to theorise that the controversy surrounding McCambridge and Dietz being uncredited may ultimately have prevented Blair from winning the award outright, though.