There's a problem with writing "monster movies": there aren't that many monsters left. It's not that we disbelieve them too much; there's always that "willing suspension of disbelief" that is the entry price for a good story, and we gladly give it. But at this point, we've befriended all the major monsters. Friendly ghosts? That's been done long since; Casper was ages ago, and Nearly-Headless Nick is just one of the more recent entries in the series. Friendly vampires? Twilight has enough of them to make a vampire soap opera. Friendly werewolves? Definitely, Twilight and Harry Potter again have the territory well-covered between Jacob Black, the Wolf pack, and Remus Lupin. The old Adams Family and Munsters were just an early act in a now-expected storyline. Wicked has a sympathetic retelling of the Wizard of Oz's Witch of the West. Even Godzilla isn't that bad, once you understand his motives. (Godzilla as an apocalyptic vengeance on man has some small similarities to the beasties of the Book of Revelation.)
So what do you do when you need a monstrous character? Well, humans have enough monstrous traits, and the other monsters were often projections of our worst selves. So storytellers generally turn to humans for their monsters. Many a story contains a "surprising" revelation that the monster is, after all, human. Environmentalists tend to write stories where humanity or industrialism or capitalism is the monster, or man is the disease that needs to be eradicated. People of a political bent tend to create caricatures of their political opponents and show them as monstrous. Or (based on J.K. Rowling's statements), people she has personally disliked over the years appear in Roman-a-clef format as distasteful characters such as Gilderoy Lockhart, or odious ones like Dolores Umbridge. (Honestly, Lord Voldemort has more a sympathetic backstory than the stand-ins for some people the author once knew.)
But what if -- what if we haven't taken "befriending the monster" quite far enough? What if the human monsters also could be understood? What if, once you understand where they're coming from, they're not quite as monstrous as we supposed? What if prejudice has blinded us, or a personal bad experience has tainted our thoughts? Why is it, again, we're so certain we shouldn't listen and seek understanding?
Once we listen to "the monster" and try to understand, the monster tends to become more human. And if we decide not to understand or listen ... well, it's easy to miss the scarier point of the "surprise" revelation that the monster is human: the monster might be us.
So here's to Halloween. It's the night where we pass out lots of candy to all the ghosts, vampires, werewolves, witches, dragons -- and neighbors -- that we might see. And for that, it may well be my favorite holiday.