|Courtesy of shlomaster|
And yet, villains affect the story more than any other single character in the book--heroes included.
For starters, the villain sets the tone of the story. The Dark Lord of Mordor and Darth Vader aren't going to inspire giggles and chuckles. And while the characters may enjoy some laughs when these guys aren't around, when they are, everything is dead serious. (Of course, we never actually get to meet the Dark Lord of Mordor, but the fact remains that he wasn't someone you want to mess with.) Whereas if you have a suave, witheringly sarcastic villain like Lord Vetinari from the Disc World Series, humor will be allowed. Granted, the characters will still be pushed out the door that has no floor, but Vetinari doesn't inspire quite the same depth of dread and darkness as Sauron does. (And yes, he is one of my favorite characters in the Disc World Series, Granny Weatherwax being the other, and possibly considered a villain from the wizards' and anyone else who gets in her way's standpoint.)
Next, and connected with the above, the villain sets the stakes. The hero isn't the one that determines what will be lost if he or she doesn't come through, that's the villain's job. Think of Lord Voldemort (is anyone else noticing the pattern with bad guys using Lord in their title?) and what it would have meant if Harry hadn't managed to survive their first encounter, let alone beat him sixteen years later. Or if Prince Humperdink had managed to kill Westley all the way instead of just most of the way. On one hand, the fate of the world and the lives of the muggles are at risk. On the other, the life of the world's most beautiful girl (at the moment) is what's on the line. The stakes are determined by the villain working in opposition to the hero. Which brings us to our next point.
No villain=no conflict=no plot=no point. Have you ever read a story where there really wasn't much of a conflict? Where everyone's out in golden fields picking lollipops while cute little bunnies frolic and the world has complete and utter harmony because there is no one to oppose this state of utter bliss? Yeah, me neither. For a story to work well, I think it has to have conflict. Something has to compel the reader to keep turning the page. If nothing is working against the hero(ine) of the story, there is no story. Stories need plot and plot needs conflict. Now, this isn't to say that all villains are humans. Nope. Some are vampires, some are inner vices like envy and greed, others are society or governments, some are as simple as really harsh settings. Like Siberia. (Or high school.) But something, somewhere, needs to be working in opposition to the star of the show, and that something is the villain.
My last point is that the villain defines the hero. Think about it. As bad as the bad guy is, the hero(ine) has to be that much better in order to triumph in the end. Imagine the story as a set of scales. On one side you have a bar of lead, on the other, a bar of gold. It isn't enough for the story to have the two bars balancing each other, one must tip the other for the reader to feel a sense of pay off. Back to Harry Potter. If Harry and Voldemort had been equally matched, well, they would have spent the eternities slinging unforgivable curses at each other or attempting to steal each other's wands. It was his mother's love that gave Harry the edge he needed over Voldemort. It protected him the first time Voldemort tried to kill him, and it protected him every summer when he went to stay with the Dursleys. And why was love the answer? Because it wasn't something that Voldemort had ever understood. Indeed, Dumbledore told Harry that if Voldemort had understood love, he never would have become Voldemort in the first place. (Which would have led to the no villain=no conflict=no plot=no point.) In fact, Voldemort defines Harry as the hero in a very literal way. If Voldemort hadn't heard part of the prophesy, he wouldn't have put stock into the prophesy, which means he wouldn't have gone to the trouble of hunting Harry down in the first place, thus creating his own mortal enemy. (Lesson here: if you're in the business of being bad, make sure you not only hear the prophesy of the chosen one in its entirety, but make sure you also understand what it's really saying.)
So whether your villain dresses to the nines, cackles and is mustachioed, or maybe doesn't own a stitch of clothing that isn't black, take a moment to thank them. Because without them, there is no hero and there is no story. And remember: villains need love too. ;-)