"Novella" is a word that may have a gajillion different definitions, most of them very similar to one another. I say "a gajillion," but more likely it's a mere few thousand. Only people who get obsessed over classifications would even bother worrying about it.
I say this upfront so as to defuse a bit of the potential controversy that might result from what titles I have and have not included on this list. It's a fairly simple process: I'm including novella-length works that did not get individually ranked on my recent Worst To Best list focusing on King's books. So in other words, the individual components of Four Past Midnight are all included, whereas a few tales which were published as standalone books -- The Colorado Kid and Gwendy's Button Box come to mind -- are not included, despite being shorter than, say, "The Langoliers."
I've argued in the past that "The Langoliers" really ought to be considered a short novel rather than a novella, but if sanity is to prevail, then such issues must be set aside fairly quickly.
And so shall they be.
Anyways, it's entirely possible some of you will think my classifications are bogus. I've eliminated from consideration anything I consider to be a short story. Some of these are stories you occasionally see listed as novellas, such as "Ur" and "N." Conversely, some of the briefer things I've included are occasionally referred to as short stories, such as "Rita Hayworth and Shawshank Redemption" and "The Little Sisters of Eluria." Bottom line is: judgment calls on my part, going with my gut. If you disagree, use them comments and tell me all about it.
So let's move on to the rankings, beginning with the cellar-dwellar:
#15 -- "The Sun Dog" (1990, from Four Past Midnight)
The fact that THIS is what I'd argue is the worst King novella indicates pretty good news for the rest of the list, because the fact is, I don't think this is too bad. Its greatest sin is that the kid who is ostensibly its hero is boring as unseasoned oatmeal. Compared to most other hero-kid King characters, he's a nonentity.
King has more success with the concept: a Polaroid camera that seemingly takes photos of a dog from another world, a dog which seems to be aware of the person taking the photo and is moving ever closer, snarling and preparing to leap from one reality into the next.
I'd argue that King does a solid job with that concept, and also with the crusty old shop owner into whose hands the camera falls. Pop Merrill -- uncle of Ace -- is a well-drawn character, and King might have been better-served to eliminate the kid and focus on Pop altogether.
So what we've got here is a case of the concept and the execution not quite measuring up. It's not bad, but we can, and will, do better.
Not immediately, though...