7. Catelyn Arresting Tyrion
More so than most other characters on Game of Thrones, Catelyn Stark has drawn the most vitriolic ire from fans. She receives an unbelievable amount of hate on message boards about her decision to release Jaime, about her absolutely abysmal treatment of Jon Snow, and about how she single-handedly started the war by arresting Tyrion Lannister. Her arrest of Tyrion for orchestrating an assassination attempt on her and Bran Stark, which was based on purely circumstantial evidence, may not have been the trigger that started the war, but it certainly didn't help her or her husband's cause. Catelyn makes the mistake that far too many people in Westeros have made: trusting Littlefinger, in this case with the knowledge that the dagger used by the assassin once belonged to him but had been lost in a bet to Tyrion. Littlefinger's is telling the truth in this case, but Catelyn takes that information and runs with it. She and her bannermen apprehend Tyrion and, without even questioning him about the matter, take him to the Eyrie to stand trial for the crime. This move draws the ire of Jaime, who leads a group of Lannister guardsmen to assault Ned and his men in King's Landing and of Tywin Lannister, who organizes his army to march against the Starks. Okay, so maybe Catelyn did start the war.