The polar opposite to Long Runners are, as you may expect, shows that were canned so quickly that few people remember them. They may have lasted one season, two at most, but no matter how much they were advertised are eventually forgotten. Some of the more unfortunate ones don't even last one episode. The Ur Example is the 1969 program Turn On which was so bad a number of affiliates dropped it at the first commercial break and was effectively cancelled before the first episode even finished airing. There's a Wikipedia article on single-episode runs.