Note:
Spoilers pertaining to The Dark Knight have been blacked out (but really, if you haven't seen the film, you shouldn't be snooping around the sequel forum yet anyway).
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I've been doing a little bit of thinking since seeing The Dark Knight, and if there is one thing I think everyone can agree on about the future of the current Batman franchise, it's that The Dark Knight brought a certain amount of escalation into the picture that just wasn't there before. With the Joker and Two-Face now introduced into the film series, the gritty realism of Batman Begins has strayed a little from being completely grounded in reality and more and more comic book elements have been introduced into the film - a move made purposefully by the brothers Nolan.
Batman has a wonderful rogues gallery - the finest of any comic book hero (in my personal opinion, alongside Spider-Man and Dick Tracy), but only a handful of said rogues would be 100% compatible with Nolan's reality-based franchise. To compensate for this, certain liberties were taken in Batman Begins - first with Ra's and the Scarecrow, to mold the characters into more believable examples. Following the introduction of the Joker and Two-Face, however, the villains have become more colorful and pulpish. This is best exemplified by Two-Face, I think. Clearly this individual could only exist in a fantasy world (the same can be said, of course, about other elements found in the film, including microwave emitters and even Batman himself - but Two-Face is visually fantastic, simply by nature).
I have seen a lot of discussion on this forum (and on The Dark Knight forum) about Nolan's next move. Where does the story go from here? Who should the villain be and how will Nolan top The Dark Knight?
It is my opinion that one of the logical choices, based upon the given story and what we know from Goyer and Nolan, is Clayface. Granted, there exists a wide variety of origins and interpretations of the Clay-Face character, and many fans aren't likely picking him for Nolan's reality-grounded world, but I think it would be a mistake to overlook him. Firstly, it has been stated time and again that Nolan is not interested in retreading any more of Batman's rogues that have been previously seen on film in previous franchises. That rules out Penguin, Catwoman, the Riddler, Mr. Freeze, Poison Ivy, and Bane (despite a few of them being fan favorites). Obviously there remains, even after that bunch, a laundry list of villains that can be picked from, including Black Mask, Ventriloquist, Killer Croc, Harley Quinn, Firefly, Deadshot, the Mad Hatter, Man-Bat, Hugo Strange, etc.
I would like to parallel the current Batman franchise with the Spider-Man films (and hope that in the process of doing so I'm not ridiculed and flamed

). The first two Spider-Man films, though clearly fantasy-based, were far more realistic than the third film, which featured Sandman as a hulking monster, Spider-Man and the new Goblin teaming up and having some mid-air hijinx, and, of course, Venom. Regardless if this was a change for the better or worse of the Spider-Man series, it's clear that the world Raimi created has gone more toward the comic book side of things than the realistic side of things. I think introducing Two-Face in The Dark Knight opened the doors to the comic book side of things for Nolan's Batman (and this doesn't necessarily have to be a negative thing).
Clayface could be handled as the character was in the Animated Series. He could start out as Basil Karlo, a B-movie, washed-up actor who uses a cream on his face to remain youthful as he desperately tries to maintain his career in the horror film industry. Of course, there is either a freak accident or a run-in with some bad dealers when Karlo doesn't pay up for his drugs (as it was presented in the Animated Series) and the actor becomes the dreaded mud-monster: Clayface (who doesn't necessarily have to be an enormous monster like Sandman was in Spider-Man 3 - but simply a man who appears to be made out of mud).
Throughout the film, Clayface could shape-shift and take on the likeness of a number of previously introduced deceased characters from the Nolan mythos, including Rachael, Thomas Wayne, Ra's, Harvey, etc. - and living characters like Alfred or Gordon - and cause a lot of trouble for Bruce Wayne, Batman, and Gotham, all the while Batman is [blackout]still being hunted down by the city's police force[/blackout]. He could even take on the form of Batman and commit further horrific crimes, creating even more distrust for Batman in Gotham. At the conclusion of the film, he could be killed or taken into custody and Batman [blackout]could be cleared of his (Harvey's) crimes from The Dark Knight and restored as a figure of hope for good people and a symbol of fear for the criminal underworld.[/blackout]
Not only is Clayface an interesting villain who has yet to see a film incarnation of any kind, but he is a villain who can be both tragic and visually appealing, while at the same time providing a new venue for continuing the story of The Dark Knight, and wrapping up the story arc that Nolan has going by bringing the series full-circle (by way of bringing back Thomas Wayne, Harvey, Ra's, etc.) and [blackout]vindicating Batman.[/blackout]
For his appearance, I would like to see a nod to the original Clayface - essentially a man made of soft mud, with the trenchcoat and hat - not a towering, top-heavy freak with crooked teeth like we say in the Animated Series.
Like it, love it, hate it? Thoughts?