Every actor has that one role they regret not taking. For Josh Hartnett, it's a doozy: the Dark Knight.

The "Penny Dreadful" star explains to Playboy that, after hitting it big in films like "Black Hawk Down" and "Pearl Harbor," he became concerned about whom he could trust in Hollywood, which led him to turn down Christopher Nolan's offer for "Batman Begins."

"I’ve definitely said no to some of the wrong people," Hartnett says. "I said no because I was tired and wanted to spend more time with my friends and family. That’s frowned upon in this industry. People don’t like being told no. I don’t like it. I learned my lesson when [writer-director] Christopher Nolan and I talked about Batman. I decided it wasn’t for me. Then he didn’t want to put me in 'The Prestige.' They not only hired their Batman for it, they also hired my girlfriend at the time [Scarlett Johansson]."

Instead, Hartnett made "Lucky Number Slevin" and "The Black Dahlia," neither of which performed very well. Meanwhile, Christian Bale starred in "The Prestige" and went on to play the Caped Crusader in all three of Nolan's Batman films.

"That’s when I realized relationships were formed in the fire of that first Batman film and I should have been part of the relationship with this guy Nolan, who I felt was incredibly cool and very talented," Hartnett says. "I was so focused on not being pigeonholed and so scared of being considered only one thing as an actor. I should have thought, Well, then, work harder, man. Watching Christian Bale go on to do so many other things has been just awesome. I mean, he’s been able to overcome that. Why couldn’t I see that at the time?"