Herrick from Being Human
Herrick may not look it, but he is one of the most terrifying vampires we have ever seen. The actor Jason Watkins that plays Herrick, gave an Oscar-deserving performance. For those who don’t know Herrick, he is a recurring antagonist in Being Human. He is a high-ranking vampire with affiliations to Mitchell.
Herrick is killed by a werewolf but is later brought back to life at the end of the first series. He returns but doesn’t know that he is a vampire. It is soon discovered to be a ruse as he returns to being an evil vampire. If vampires were real, you don’t want to run into a Herrick.