Genre is a fluid thing. Is Zombieland a horror movie or a comedy? Is the original Saw a slasher or a thriller? Everyone has their own idea of what is horrifying, and what should be classified as horror. I think that I have grown up with a pretty conventional idea of what horror is: something that aims to scare you, to get a reaction on a primal level. Some giant monsters and a few buckets of blood don't hurt either. Unfortunately, horror still has a stigma, that it is mindless, simple, and isn't taken seriously. Many "mainstream" directors incorporate dark subject matter into their films, but haven't taken that jump into full-fledged horror. Below are four directors whose style lends itself to full-out horror.
Chris Nolan has always been on the verge of the horror genre. His take on Batman is far darker than Tim Burton's was. His breakout film, Memento, involves a man with no short-term memory who tattoos himself in order to maintain memories as he hunts down his wife's killer. Insomnia is another murder mystery, this one set in a northern town where, at this time of year, the sun never sets. The Prestige is about rival magicians, one whose illusion becomes a lifelong pursuit and the other who turns to science in order to create real magic. His last film, Inception, goes further into the fantastical with a process of going into people's dreams in order to change memories. All of these films are just a few big scares, a higher body count, or a supernatural creature away from being full-fledged horror. Nolan has said that his version of Bane, the villain in his upcoming The Dark Knight Rises, is inspired by classic horror movie monsters. I could totally see Nolan taking on a true ghost story or bizarre serial killer story, maybe with a supernatural slant.
Best known for his intense action flicks like Snatch and Lock, Stock, and Two Smoking Barrels, and the recent Sherlock Holmes films, Guy Ritchie has a visual style that is often imitated but scarcely matched. I could see him doing an intense cat-and-mouse slasher flick, or something along the lines of Ghost Rider (but more intelligent). Maybe a mafia member falls afoul of his family, loses his money, turns to black magic to repay his debts, and eventually is running from the mob boss and a demon.
The Coen Brothers
Joel and Ethan Coen are the modern-day masters of noir, and noir isn't far off from horror. Noir relies on a a dark, shadowy setting to invoke tension and mood. While noir doesn't generally have a supernatural or "crazed" aspect, there is always an air of danger; the murderer could be behind every door, down every alley, lurking in every shadow. The Coen brothers would, of course, have to do a horror comedy. The Big Lebowski is one of the funniest films of all time. Fargo stands as one of the quirkiest murder mysteries out there (with a body-in-the-wood-chipper scene that made "mainstream" viewers shudder). No Country for Old Men was dark and violent. And Intolerable Cruelty was the most horrifically awful film I have ever had the displeasure of seeing.
It is kind of surprising to me that John Waters has yet to direct a horror film. He enjoys horrifying audiences with gross-out scenes (Pink Flamingoes), subverting Hollywood cinema (Cecil B. Demented), and is obsessed with serial killers (Serial Mom). John Waters couldn't make a "serious" film to save his life (goodness knows I sure as hell don't want to see him go serious). Waters needs to go tongue-in-cheek with a horror movie. I'm thinking deranged clowns versus porn stars versus piranhas. And rivers of blood.