9. Rosanna Cavalierri (The Vampires Of Venice)
Rosanna was the matriarch of the Saturninans, fish people who manifested as vampires thanks to the use of a perception filter - thats probably something only Doctor Who could hope to get away with. Her plan is merely the continuation of her species but she does this via luring girls to her school and forcing their transformation into suitable mates for her many sons hiding in the water. A plan that, when you stop to think about it, is actually quite horrifying. What makes Rosanna so utterly monstrous, and such a good villain, is the fact that she doesnt care about the girls at all - apart from what they represent as a means to an end. She doesnt take time to notice them, suggesting she views humanity as utterly inferior. This is what irks the Doctor enough to destroy her - she cant even remember the names of the girls who have become her victims. Despite this, though, what makes Rosanna such an interesting character is that she manages to be tragic. She does despicable things, and does them with a cocky verve, but her final appearance makes her sympathetic by showing that she was just trying to save her species. Her final challenge to the Doctor is poignant and thought-provoking, staying with the viewer after the final credits and raising the question of whether what the Time Lord does is actually right. All in all, certainly worth the watch.