There aren't a lot of things more frustrating than an almost-classic film.
You know the phenomenon. These aren't three star efforts which could have been contenders that are being discussed here. No, these are the movies which come close to five star perfection for most of their runtime, with a stellar cast, a perfect conceit, and effective direction...
Only for one fatal flaw to ensure it'll always be stuck in "not quite, but almost perfect" territory.
Horror is particularly susceptible to this phenomenon as a genre, as there are plenty of stumbling blocks set out by its rules. A monster movie can be brutally effective until viewers actually get to see the laughable creature, ghost stories can be chilling until a convoluted backstory overcomplicates proceedings, and incredible slashers can be undone by one lame kill or a silly killer reveal (Kirby should have lived and you know it, Scream 4).
Some are utterly derailed by this pivotal problem, some are still classics but fall at the last minor hurdle, but in each case, these are ten horror films which were one fatal flaw from being perfect pieces of genre fare