She may have gone darker just for kicks, but it's possible it's for a film role. Back in August, Dakota and Jesse Eisenberg were reportedly in talks to star in a new thriller called Night Moves, which was supposed to start filming right about now. Dakota was reportedly taking a role previously offered to Rooney Mara. Rooney is a brunette (not always black like Girl With a Dragon Tattoo, but not blonde either), so it's possible Dakota went dark for the part. That's just a guess, though.
Either way, she looks good! But do you think she looks better as a blonde? At least now people will definitely be able to tell her apart from her younger sister, Elle Fanning!