The Exorcistmight be one of the greatest horror films of all time, but only one other movie in the long-running franchise is even worth watching. Based on the eponymous novel by William Peter Blatty, 1973's The Exorcist delivered the most frightening cinematic experiences moviegoers had ever seen up to that point, and has rarely been matched in terms of quality. The tale of a little girl getting possessed by a malevolent demon was harrowing enough, but director William Friedkin's insistence on grounded filmmaking made everything all the more nightmarish because it felt so real.