Only one show in U.S. Broadcast history has ever been canceled while it was on the air- the ABC sitcom Turn On.
The show was meant as ABC's version of NBC's successful Laugh-In and featured Tim Conway as its first guest host in February of 1969. Apparently Mr. Conway was seen as being "Too Hot for TV" at the time, because several affiliates pulled the show while it was still airing and ABC chose to cancel the show before it had ended. Other than the title card, not much footage remains of the first or second episodes, the only ones produced. We can only imagine the wacky hi jinks that Tim Conway must have gotten himself into. Apparently only Carol Burnett was willing to unleash Mr. Conway on the world after this racy broadcast.
Amusingly, the failure of this show made ABC leery of making any risky choices thereafter and they rejected All in the Family for being too controversial. After all, if America couldn't handle Tim Conway on their screens, they certainly weren't ready for Archie Bunker.
