Christopher Nolan is currently at work on one of the most highly anticipated superhero films yet - The Dark Knight, sequel to the critically acclaimed Batman Begins. In an interview with Wizard Entertainment, Nolan took the time to address some of the rumors and speculation surrounding the film.

Nolan spent most of the interview discussing the somewhat controversial casting of Heath Ledger in the role of the Joker, Batman's most iconic villain. Following up Jack Nicholson's take as the Joker in Tim Burton's Batman is a challenging task, and one that many fans worried Ledger wasn't up to.

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Nolan, however, had no such doubts:

I was looking for someone who was fearless. I knew that I needed a fantastic actor, but I also knew that I needed someone who wasn't going to worry about comparisons to any other actors who had played the role. I met with Heath before we even actually had a script. We talked about ideas for who the character would be in this movie as opposed to his previous appearances in movies, and we both saw it in the same way. He's just an incredible, incredible actor, and if you see Brokeback Mountain, it's an amazing performance from a young actor. It's just this sort of youthful energy that he has and the kind of intensity that he brings to this process has been pretty extraordinary to watch.

When asked specifically about whether he had any fear of Ledger being compared unfavorably to Nicholson, Nolan answered "Oh, not particularly. Jack Nicholson did a very definitive portrayal of a type of Joker; a version of the Joker in the Burton film that has lasted as an icon. We were always going to come up against that so I didn't particularly worry about it. Also, Heath is one of those actors who, in his best work, completely transforms himself and that sort of consumes his star quality. He's creating something that's entirely original for himself and so he's never done anything like this before. I can't say that I was hugely surprised or worried about the reaction because whoever we would've cast, it's going to be tough for people to know how the palette is going to work. Particularly with Heath, who's dredging something up from a side of himself that you've never seen before."

Nolan also discussed his thoughts about the Joker as a character, and what his relationship with Batman is. "The Joker, in his own way, is as much an icon as the Dark Knight is and that presents us with just a tremendously exciting opportunity in terms of how we carry on our story and continue to explore the point of view of the character because, as I said, he is as almost as much an icon as Batman himself. It's a pretty terrifying spectacle, and he's a really fascinating character...We want to create a villain who, as colorful and eccentric as he is, it's still coming from a place of psychological reality. It's coming from a recognizable, everyday reality. So the notion of the Joker as the most extreme form of anarchist, the most frightening form of anarchic, chaotic presence in Gotham, that's very much the starting point for the character and very much what the character has become."

When asked whether Harley Quinn, the Joker's one-time psychologist turned girlfriend and criminal sidekick, would be appearing, Nolan just laughed and said "It's all a rumor."

Asked if The Dark Knight was the last film in the Batman franchise for Nolan, the director explained that he believed it was, but he was unsure. "I never thought that I would do a second "Batman" film. Let me put it that way. I had no thought of doing a second one when I was doing the first one, but obviously you never say, "Never." Every film I'm working on, however, to me is generally the last film I'm ever going to make. That's my approach to making film." He continues, "I'm very single-minded and very focused on the task at hand and I do focus on just this movie. I really don't have anything in my head about what's next or doing another one or whatever. "

CLICK HERE to read the full interview with Christopher Nolan.

The Dark Knight opens on July 18, 2008, and stars Christian Bale, Heath Ledger, Morgan Freeman, Gary Oldman, Aaron Eckhart and Maggie Gylenhall.