Knightley has come under fire for her teeny frame, but she has denied ever having an eating disorder.
She sued the British tabloid Daily Mail for a story she said insinuated that her own weight contributed to the death of a 19-year-old woman who had anorexia. Knightley won £3,000 in damages plus legal costs from the paper in 2007, the Guardian reported.
Later that year, while promoting Atonement at the Venice Film Festival, she lamented over how the topic of her weight was being brought up again -- and taking attention away from the film.
It's really frustrating, and particularly when you come to Venice film festival with a film that is an intelligent film, she told Reuters. It's a thought-provoking film you can have a really good discussion about. I think it was just a shame that that had to be brought up then, and the fact that we all knew that it was going to be brought up.
Knightley's upcoming projects include Seeking a Friend for the End of the World, opposite Steve Carell. The film is scheduled for a US release on June 22. She will also play the title role in Anna Karenina, which is scheduled to hit US theaters on Nov. 9.
In celebration of her 27th birthday, here are some of Knightley's best red carpet looks.
Keira Knightley in 2003 at the premiere for "Pirates of the Caribbean: The Curse of The Black Pearl." Reuters
Keira Knightley in 2005 at a premiere gala for "Pride and Prejudice." Reuters
Keira Knightley at the Oscars in 2006. Reuters
At the European premiere for "Pirates of the Caribbean: Dead Man's Chest" in 2006. Reuters
Keira Knightley is 27 years old. Reuters
Keira Knightley in 2010. Reuters
Keira Knightley in 2008 at the world premiere for "The Duchess." Reuters