Klaus Mikaelson, an Original vampire, and the first hybrid (vampire and werewolf) who ever existed has been making quite the impression since way before an actor for him had been cast. Joseph Morgan didn't appear until the end of season two after Klaus possessed Alaric's Saltzman's body. This man is known for how violent and terrifying he can be. Viewers witnessed his violent acts through season two and three, but he has been causing trouble for centuries. Executive Producer Julie Plec has said that at the end of season three the plan was to kill off Klaus so that the heroes could prevail. Due to how phenomenally Joseph portrayed the villain, the writers decided to keep him alive so that he could continue to evolve through season four.