Hilary Erhard Duff (born September 28, 1987) is an American actress, pop singer and entrepreneur. She has an elder sister, Haylie Duff, who is also an actress/singer.

After gaining fame for her starring role on the television show Lizzie McGuire, Duff went on to have a film career, and her most commercially successful pictures include Cheaper by the Dozen (2003), The Lizzie McGuire Movie (2003), and A Cinderella Story (2004). She reportedly earned $15 million in 2005. Duff has expanded her repertoire into pop music, with three RIAA certified-platinum albums and over thirteen million albums sold worldwide, and she has launched a clothing line, Stuff by Hilary Duff, and an exclusive perfume with Elizabeth Arden. Duff and her mother were listed as producers for the movie Material Girls and will soon produce her sisters debut album.

Her upcoming films include the 2007 action thriller War, Inc. and animated comedy Foodfight!. Duff's latest studio album, Dignity, was released in April 2007 and has sold 801,950 copies worldwide to date.