There is actually a Wikipedia category on this subject. But more often: There are lots of unfinished books by authors, either because they died before they finished them, or because they never felt what they were writing worked. (In some cases authors have actually published unfinished books, knowing they will not be able to finish them but still wanting to put out what they have finished.) Similarly, there are unpublished books by authors. I suppose the equivalent of a canceled TV series would be an unfinished book series.