The Exorcist controversy

The Exorcist - Original Theatrical Trailer is the trailer for the 1973 film The Exorcist, made for Warner Bros., that contains screamers. The film features Regan MacNeil and Pazuzu, two well-known figures in the world of horror and screamers. This trailer eventually got banned due to the following reason, as described in a 2009 mirror upload by ShortFormCinema:

"The original (rare) 1973 theatrical trailer that film executives banned due to the concern that the content within was too disturbing for audiences."

The trailer begins with the voice of the demon Pazuzu, together with some uncomfortable music on the background. A taxi stops at the house of Regan MacNeil, the girl who got possessed by Pazuzu. Father Merrick, the person who is being called to save Regan after Pazuzu possessed her, is seen leaving the taxi, with a voice-over on the background saying: "Something beyond comprehension is happening to a little girl on the street, in this house." As the taxi leaves and Father Merrick is about to enter the house, the voiceover continues saying: "A man has been sent for, as a last resort, to try and save her."

Immediately after that, a long montage of flashing images of Regan, Pazuzu and Father Karris, the assistant of Father Merrick, appear with very disturbing music on the background.

Apparently, this trailer alone was so disturbing that viewers cried, vomited or even fainted after seeing it. One reason for all of this is that people in 1973, the year the actual movie was released, were not ready for it because of the stunning special effects at the time.

Links
NOTE : The following video contains screamers with flashing lights
 * Official upload: youtube.com/watch?v=jyW5YXDcIGs
 * 2009 mirror: youtube.com/watch?v=u15h02Y0MDY
 * Higher quality: youtube.com/watch?v=6XuB8DJ0AI8