Has to be Dan Brown, doesn't it? I've only read Angels and Demons, but the characters were so utterly vapid and unsympathetic, the writing was so grotesquely sub-sub comic book, and the plot was so hopelessly preposterous that it was offensive in every way - the only way it could have been worse is if it came around to my house and left a turd in the kitchen before burning down my street. Which, coincidentally, is what would happen to Dan Brown, in a kind universe.
Someone gave me a couple of books by Maggie Furey a while back, which were tedious, formulaic fantasy fiction, and didn't have any of the North East flavour I might have expected from a Newcastle author. Fair enough, so far so whatever, but the lazy cow was too idle even to bother tidying up the plot strands in the course of the rushed ending. Whoops, I forgot about the marauding Demon King who was laying waste to the cities. Oh well.
Also Stephen King. The books make good movies/doorstops/kindling, but you wouldn't want to read one of them.