Ros was a different character to the others on this list as she has no counterpart in the books, so even those who have read them didnt know what would happen to her. She originated in Winterfell and was working as a whore for Littlefinger, but in the end she was secretly spying on his activities for Varys and this is how her death came about. Because one way or another, Baelish found out about her activities and took action to end it. He gave her as a gift to Joffrey, who had previously forced Ros to beat another prostitute with a sceptre at the threat of being skewered by a crossbow. That would be the weapon of choice for Joffrey to kill Ros, as he decides to try his hand at shooting a live target tying her to his bed and shooting her full of bolts. It was this dispassionate action and the way her corpse was shown which was used to demonstrate a change in Joffreys actions. He went from a snivelling boy who didnt care about the results of his own actions to a sadistic King who would be dangerous for anyone to be around.