Well, two of the most psychologically intriguing villians from Batmans rogues gallery were in The Dark Knight, and we can be positively sure they won't make an appearance anymore.
With the Riddler, the Scarecrow, Ra's Al Ghul and the Pinguin ruled out, the most interesting ones would be either Bane or Catwoman (but they would need one hell of a good script/actress to get her to be equally awesome as Ledger's Joker), so I'm guessing Bane. And not the one from the previous series of films, but the one of the comics. The one that's both genius and strong enough to snap Batman in two like an old straw. But I have a slight feeling that won't be happening, since Bane is mostly a physical threat to Bats (he actually broke his spine in the comics), and the Joker/Scarecrow/Ra's/Two-Face have all been mostly psychological adversaries. I know Batman has a ton of other enemies to choose from, but many of them actually have superpowers or some gross, unnatural anomaly, and the serum Bane uses to get so insanely strong is the closest thing to remotely scientifically explainable, like pretty much everything in Nolan's Batman-series has been so far.
Anyway, I'm most eager to find out and I'm sure Nolan won't disappoint us
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With the Riddler, the Scarecrow, Ra's Al Ghul and the Pinguin ruled out, the most interesting ones would be either Bane or Catwoman (but they would need one hell of a good script/actress to get her to be equally awesome as Ledger's Joker), so I'm guessing Bane. And not the one from the previous series of films, but the one of the comics. The one that's both genius and strong enough to snap Batman in two like an old straw. But I have a slight feeling that won't be happening, since Bane is mostly a physical threat to Bats (he actually broke his spine in the comics), and the Joker/Scarecrow/Ra's/Two-Face have all been mostly psychological adversaries. I know Batman has a ton of other enemies to choose from, but many of them actually have superpowers or some gross, unnatural anomaly, and the serum Bane uses to get so insanely strong is the closest thing to remotely scientifically explainable, like pretty much everything in Nolan's Batman-series has been so far.
Anyway, I'm most eager to find out and I'm sure Nolan won't disappoint us