Count Dracula
Whether the reader believes that the character was based on Vlad III Tepes or not is irrelevant. What is relevant is that the Count is among the most enduring, most powerful villains to have ever appeared in any format. Yes, he was a monstrous fiend in the end, but his charming and elegant demeanor were a contrast to the portrayal of villains during his time. Like real serial killers, Dracula did not look particularly out of place among normal people. In the novel, most people found him odd only because he was not native to England and many things about him were foreign to others. He is among the best examples of literature that shows that the villain can be just as human as the hero, and need not always be a fierce dragon or ancient, overwhelmingly vile demon.
Darth Vader
Even when considering the disappointing nature of the prequel trilogy, it is difficult to deny that Darth Vader served as not only the villain, but the core of the “Star Wars” mythology. His actions shattered a generations-old order and, later, helped shape the galaxy for generations to come. His imposing presence, in his black armor and the distinct sound of his breathing, was enough to instill fear in those that stood before him. The fact that he was more than willing to do the dirty work, something most modern villains hardly ever do anymore, made him that much more convincing as an instrument of oppressive, dominating power. It is true that Luke Skywalker and the other heroes of the “Star Wars” saga had the spotlight on them, but most critics would agree that the sheer presence of a character like Darth Vader was what made the movies such successes.
The Joker
It takes a very special mix of evil and insanity to make the image of a jester into one that instills fear even in other villains. In the universe of DC Comics, this was a feat achieved only by the notorious Joker. The Joker lacks the tragic background elements that made Vader and Dracula such sympathetic villains, but then, his is a character that wasn't designed to instill sympathy. The Joker's primary goal is to kill as many people as he could, preferably in the most comedic (in his mind) manner possible. Some argue that his near single-minded obsession with that goal is a dark mirror to Superman's own single-minded pursuit of good. However, in some ways, The Joker is still best served as a foil for The Batman, with the former using objects meant to spread joy in murderous ways, while the latter uses criminal tactics to enforce the law.
Hannibal Lecter
Villains, by some unknown token, tend to be portrayed as brutish and rough. Most people would expect the villain to look hideous or monstrous, the better to inspire the fear he uses so effectively as a tool. However, Hannibal “The Cannibal” Lecter deviates from that tradition, and he does with such class and grace that he makes his own villainous activities look appealing. To make a man with activities as monstrous as Lecter's look appealing, noble, and even admirable takes a special kind of personalty. Hannibal Lecter is arguably among the greatest villains of all time, with very few having any credible right to compete against him.
Indeed, villainy is more than just being the “bad guy.” Behind the fiendish laughter and the menacing costumes lurk a deeper, and not always sinister, personality and motive.