The worst for me were the Lord of the Rings movies. They probably would have been awesome fantasy movies if I didn't feel the need to stab Peter Jackson every second of them. I can understand some cosmetic changes like in Watchmen (alien attack vs Manhattan attack), but I cannot understand when a dorky movie director of bad taste and braindead decides he can actually change whole aspects of a classic saga. (And after all those added Arwen scenes he could've at least shown that in the end Arwen regretted and was bitter as per the appendices of RotK novel.)