1. Troll 2
One would think that the terrible film Troll wouldn't have a shark to jump until you watch Troll 2, a movie of profound and transcendent incompetence. Troll 2 jumped the Troll series' shark so badly it didn't even have the good taste to include an actual Troll in the film. Since it was unleashed in the world, lovers of bad cinema have heralded it as the pinnacle of unintentional hilarity. It developed such a cult fanbase that a 2009 documentary Best Worst Movie chronicled the making of the film and the huge following it garnered. Conceived as an anti-vegetarian screed (I'm not joking) Troll 2's primary antagonists are goblins who have the power to turn people into vegetables, which they then consume. The goblins' costumes consist of potato sacks and sub-halloween goblin masks:
The Italian director and crew didn't speak English and insisted that the script, comprised of pidgin English, be read verbatim by the English-speaking actors without allowing them to correct grammar or syntax. This painfully stupid decision resulted in one of the greatest pieces of anti-cinema ever put to celluloid. I cannot recommend it enough to those who watch love to watch so-bad-its good movies. It never fails to crack me up. So there you have it, 8 more franchise killers. Please let me know in the comments what other terrible sequels I missed.