The Exorcist controversy

The original theatrical trailer for the 1973 supernatural horror film The Exorcist, made for Warner Bros., contains disturbing imagery. The film features Regan MacNeil and Pazuzu, two well-known figures in the world of horror and screamers. Before the actual movie was released on December 26, 1973. This trailer spawned controversy 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 Pazuzu (portrayed by Eileen Dietz and voiced by the late Mercedes McCambridge), together with some uncomfortable music in the background. A taxi stops at the house of Regan MacNeil (portrayed by Linda Blair), the girl who got possessed by Pazuzu. Father Merrick, the person who's getting called to save Regan after Pazuzu possessed her, is seen leaving the taxi, with a voice-over in 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 Karras, the assistant of Father Merrick, will appear with very disturbing music in the background.

Controversy
This trailer alone was so disturbing that viewers cried, vomited, or even fainted after seeing it. One reason for all 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 videos contain 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