Anyone else still thinking about Keira Knightley's backless green dress from Atonement, 13 years later? At the link in bio, our style editor examines why the backless trend became an unlikely A dress so iconic the original went missing! Keira Knightley's emerald silk gown in Atonement wasn't just the green dress it was the moment. Custom dyed, cut on the bias, and L'actrice Keira Knightley pose un photocall du film 'Atonement' l'ouverture du 64me Festival du Film International de Venise au Palazzo del Casino de Venise, Italie, 29 aot 2007. Photo : November 2009 hannah couture Keira Knightley Green Dress in Movie Atonement Keira Knightley cuts an elegant figure in a strapless dress while Shanina Shaik flashes her sideboob in a racy ensemble at as they lead the stars at Tod's Milan Fashion Week show