Hilary Erhard Duff is an American actress, pop singer/songwriter and entrepreneur. She has an elder sister, Haylie Duff, who is also an actress/singer. After gaining fame for playing the title role in the television show Lizzie McGuire, Duff went on to have a film career; her most commercially successful movies include Cheaper by the Dozen, The Lizzie McGuire Movie, and A Cinderella Story.