The film climaxes with Karras and the elderly Father Merrin (Max Von Sydow) performing the exorcism heard 'round the world.

The site adds that the book and subsequent "Exorcist" movies confirm the demon's name. If you pay close attention to the film, the name makes sense. At the beginning of the movie, Father Merrin ...

So extreme were viewers' reactions to "The Exorcist," the ... call in Fathers Lankester Merrin (Max von Sydow) and Damien Karras (Jason Miller) to exterminate the demon Pazuzu.