10. Professor Moriarty

BBCNo, not specifically the Moriarty shown above, but a version of him tailored for the horror setting of Penny Dreadful's Victorian London would be a good fit. It would introduce a more human enemy for the gang to square off against and in a world without Sherlock Holmes (which it would have to be for this to work) how terrifying would the presence of the Napoleon of Crime be? Who could stop him? Of course it'd be tough to try and top the various decent depictions of Moriarty that an inclusion like this would inevitably draw comparisons to. Both Jared Harris' steely confident portrayal and Andrew Scott's chew-the-furniture lunatic approach are either end of the spectrum here. We think Penny Dreadful's version should fall somewhere in the middle, mostly quiet but prone to fits of madness. Perhaps Fringe's John Noble is a good choice?