This is Carl's Brain
Top Ten Horror Movies of All Time: Number 2 – The Exoricist

The Exorcist is without a doubt, in my humble opinion, the scariest movie ever made, in fact, the only movie that ever truly scared the wits out of me.  It probably doesn’t help that I was nine years old the first time I saw the movie, and I was alone late night in an empty movie theater with my wife the second time I watched it. The movie has lost absolutely none of its magic since it was first released in 1973.  So many movies since then have tried to be like The Exorcist yet none can capture the sense of peril and fear created by the original, even subsequent sequels and remakes.  Linda Blair did an excellent job as a child in severe distress.  Interestingly enough Marlon Brando and Jack Nicholson were originally going to be cast in the roles of the priests in the movie, which would have made it something entirely different.  Although there were so many great aspects to the movie, most notably the atmosphere of it , what really clinched it for me was Regan’s 360 head spin and crab walk down the steps.  Watch it only if you dare.