The leading ladies of movies, music and television gave us a supersized dose of style last night! In Los Angeles, Halle Berry (in vintage Roberto Cavalli) and Katie Holmes (in a Madewell dress and Lanvin blazer) joined gallery-goers for the opening of Beauty Culture at the Annenberg Space for Photography, while Kristen Bell walked the red carpet at the premiere of The Hangover Part II in a light-as-air silk chiffon dress by J. Mendel. In New York City, Rachel Bilson debuted not one, but two gorgeous ensembles from Chanel as she made the rounds to promote her new television series, Hart of Dixie. And in Cannes, Gwen Stefani got heads turning (and jaws dropping!) in her flawless custom L.A.M.B. gown at the 2011 amfAR Cinema Against AIDS gala. Click here to see the hottest star looks at last night's parties!