Bat-Mite is Batman's biggest fan, who also happens to be from another dimension. He has seemingly magical powers, much like Superman's foe Mxyzptlk, but rather than using them to create havocc like Mxyzpltk, Bat-Mite just creates scenarios where he can observe Batman's heroism.
After DC Comics rebooted their universe in the 1980s, Bat-Mite mostly disappeared until recently. In the current continuity, Bat-Mite is an element of "The Batman of Zur En Arrh," a persona Batman implanted into his subconscious that takes over if Batman loses his mind. The whole Zur En Arrh thing seems kinda dumb to me, but it's nice to see Bat-Mite back.
Pros: A little dude in an ill-fitting Batman costume with magical powers playing games with Batman? There's something pretty awesome about that.
Cons:None of that belongs in the kind of world where The Dark Knight takes place.
How I'd do it: Gotham toy makers try capitalize on the news about Batman by selling Batman toys that look like Bat-Mite?
Casting Guesses: No one? If they really want to to Bat-Mite, it should be CGI.
After The Scarecrow, Ra's Al Ghul, The Joker, and Two-Face, who should be Batman's next enemy in the Batman Begins/The Dark Knight series? Well, as of now we know that Tom Hardy will play Bane and Anne Hathaway will play Catwoman.
Check out the master list for all the villains covered. I've pretty much run out by now. Obviously, there are more Batman villains, but not any of significance that I know of. As of February 2009, no one is confirmed as a villain. Not the Johnny Depp Riddler, not Phillip Seymour Hoffman Penguin, nobody.