With The Dark Knight set to break box-office records, a sequel is almost certainly in the works. With Heath Ledger and Aaron Eckhardt's masterful performances as The Joker and Two-Face, respectively, finding another villian or two to ably face off against the caped crusader, while staying true to Christopher Nolan's darker tone won't be an easy task. Here's 5 villains that may be able to pull it off.

5-Dr. Hugo Strange

Character's effectiveness and value: While Dr. Hugo Strange might not be very physically intimidating or threatening, his mental prowess and ingenuity make him a credible foe.  His comic book schemes have included massive, genetically-engineered monsters that attack upon command, and the discovery and attempted auction of Batman's secret identity.  He was also one of the first reoccurring Batman villains, appearing before both the Joker and the Catwoman.

Character's potential for realistic portrayal: The not-so-good doctor would easily lend himself to a practical portrayal, especially since his costuming would probably only include a lab coat and some Windsor glasses.  There also seems to be a degree of mistrust with today's medical field and its practitioners, and the filmmakers could certainly tap into that fear when developing this character.

Influence of previous interpretations: Aside from one or two animated Batman episodes, Dr. Strange has been sparsely utilized on screen making him a character that has little previously-established bias.

4-The Penguin

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Character's effectiveness and value: One of the most glaring weaknesses of the Penguin is his lack of menacing qualities.  He's short, obese, and chain smokes, meaning his athletic prowess is pretty low.  That being said, he does have an extremely rich history in Batman lore, and his character has been thoroughly fleshed out resulting in more depth than your average villain. 

Character's potential for realistic portrayal: The Penguin is another character that would translate fairly easily into film.  He seems to favor formal clothing, but given his physical attributes, masking his insecurities with feigned affluence seems natural.  At one time the Penguin was rumored to be cast in The Dark Knight as a British arms dealer, which lends further credence to the idea that he could be done realistically.

Influence of previous interpretations: There have been a myriad of Penguin portrayals all of varying degrees of quality, so it would be tough to escape any foregoing prejudice and this could be seen as another weakness for the character.  Hopefully that won't dissuade the usage of him because there is an underlying creepiness with the Penguin, and as we saw with Christopher Nolan's Joker, creepiness is something that he seems to do well.

3-Mr. Whisper

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Character's effectiveness and value: Mr. Whisper was said to be an ancient monk who sold his soul to the devil in exchange for eternal life, and an immortal would likely make a very formidable villain.  In the comic Batman: Gothic, the shadowless Mr. Whisper runs amuck in Gotham, slaying numerous mob bosses in an attempt to win back his soul.  Batman repeatedly does battle with Whisper, but it's especially tough to defeat someone who's death-resistant when you've taken a vow not to kill.

Character's potential for realistic portrayal: Mr. Whisper's outside appearance would not be a problem in terms of rational depictions, but the fact that he survives falls from skyscrapers and head-on collisions with trains might seem a bit too improbable for the next Batman movie. An ambiguous approach to Mr. Whisper's perceived powers might be the best way to portray the character on film, keeping the audience guessing whether or not he really is superhuman.

Influence of previous interpretations: As previously mentioned, Mr. Whisper can only be found in the graphic novel Batman: Gothic, and as a result there haven't been any distorted interpretations done.  So if Mr. Whisper was utilized, no audience member would have any preconceived partiality.

2-Zsasz

Character's effectiveness and value: Zsasz is a serial killer who cuts tally marks into his skin after each subsequent murder.  He regularly refers to his victims as zombies and he insists that he's liberating them from pointless existence by slitting their throats.  He briefly appeared in Batman Begins as an inmate in Arkham Asylum where he was identified as a hitman for the mob.  During the film, his recognizable scars could momentarily be seen during his escape from Arkham.

Character's potential for realistic portrayal: His potential is obviously very high since he has already been imagined and introduced into the film's universe. 

Influence of previous interpretations: Beyond the comic books, the only other source where Zsasz can be found is in the Batman Begins movie, and as a result the character hasn't yet been tainted by any earlier distortions.  So a more fleshed out and prominent role in the ensuing film would set the cinematic interpretation standard.

1-Deacon Blackfire

Character's effectiveness and value: While less of a preacher and more of a cult-leader, Deacon Blackfire led a band of brainwashed Gotham citizens into what he described as a war on crime.  Eventually this cult took over all of Gotham resulting in its segregation from the rest of the country.  At one point a weakened Batman had even become an indoctrined sect member; however, by the end of the story he realizes the error of his ways and beats the reverend senseless.

Character's potential for realistic portrayal: There really isn't anything too unusual or improbable about the deacon to warrant not including him in the movie.  While Blackfire makes claims that may seem too sensational for the film, specifically regarding the immortality he receives by bathing in blood, by the end of the comic we find out that indeed the deacon was more of a conman than immortal, firmly grounding the story in reality.

Influence of previous interpretations: The graphic novel Batman: The Cult is the only source where Deacon Blackfire can be found, so again, there aren't any other representations of this character to muddle his prospects.