Max Headroom broadcast signal intrusion

The Max Headroom broadcast signal intrusion was a television signal hijacking that happened in Chicago, Illinois, United States, on the evening of November 22, 1987. It involved at least three unknown people. It is an example of what is known in the television business as broadcast signal intrusion.
Two Chicago television stations, WGN-TV and WTTW, had their broadcast signals hijacked by an unknown person wearing a Max Headroom mask and sunglasses. A homemade Max Headroom background rocked back and forth in the background. The incident happened two times within a course of three hours.
The first incident took place for 25 seconds during the sportscast on the 9:00 PM news on WGN-TV Channel 9, and the second, two hours later, after 11:00 PM on PBS related WTTW Channel 11 for about 90 seconds during a broadcast of an episode of the "Doctor Who" serial "Horror of Fang Rock".
The incident made national headlines and the people responsible have never been identified.