Hilary Erhard Duff (born September 28, 1987) is an American actress, pop singer-songwriter and entrepreneur. 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 (2003), The Lizzie McGuire Movie (2003), and A Cinderella Story (2004).

Duff has expanded her repertoire into pop music, with four RIAA certified Platinum albums and over thirteen million albums sold worldwide. Her first studio album, Metamorphosis (2003), was certified triple platinum and she followed it up with two more platinum albums, Hilary Duff (2004) and Most Wanted (2005). Duff's last studio album, Dignity, was released in April 2007 and was certified Gold in August 2007.

She has also launched a clothing line, "Stuff by Hilary Duff", and two exclusive perfume collections with Elizabeth Arden. Duff and her mother were listed as producers for the movie Material Girls, As of August 2008, her upcoming films include animated comedy Foodfight!, and independent films Greta and Safety Glass.