For Lively, who's known primarily for her work on the TV show "Gossip Girl" and for her sense of fashion on the red carpet, going brunette was just the beginning to get her character just right.
"The comics have been around for so long," said Lively. "And there's such a devout fan base that you have to be true to them. So changing the way I look, stepping into that and doing the flight training. Getting used to the G-suits and putting them on and getting used to the compression suits. It was so much fun."
Lively gets a workout, but one moment the studio did not release involves her just lying suspended in air. It was far from easy to accomplish.
"You're wearing this gyroscopic waist belt and you have to keep your body perfectly flat," said Lively. "You have to look like you're just unconscious and effortless, but not be trembling while you're on this thing that's just spinning. It takes an unbelievable amount of core strength and I had to work out for months to just do those 10 seconds of effortless floating."
"Green Lantern" is full of high-tech special effects, but beyond the big budget spectacle of it all Lively was thrilled at something else much more simple.
"I saw a Barbie sitting there with my face and my mole, I could not believe it," said Lively. "That was a huge deal for me. I never even thought I would be an actor and then have my own Barbie."
So does that make Reynolds Ken?