Sienna Rose Diana Miller is an American-British actress and model known for her roles in independent films and mainstream blockbusters. Born on December 28, 1981, in New York City to an American investment banker father and a British-South African art dealer mother, she was raised primarily in London after her parents' divorce. Miller began her career as a model, gracing the pages of Italian Vogue and posing for the 2003 Pirelli Calendar. Her acting breakthrough came in 2004 with supporting roles in the films Layer Cake opposite Daniel Craig and Alfie alongside Jude Law, which brought her international attention and established her as a rising star in Hollywood and British cinema.

Miller's career progressed with notable performances as socialite Edie Sedgwick in Factory Girl (2006) and author Caitlin Macnamara in The Edge of Love (2008), earning her a nomination for the BAFTA Rising Star Award in 2008. She took on action roles, including The Baroness in G.I. Joe: The Rise of Cobra (2009), but faced intense media scrutiny that led to a brief hiatus from acting. Miller became a prominent victim in the News of the World phone hacking scandal, where she was revealed as a victim of invasive tabloid practices by Rupert Murdoch's News International. She successfully sued for invasion of privacy, receiving a substantial settlement in 2011 and becoming a vocal advocate for press reform in the UK. Her later work includes acclaimed supporting roles in films like Foxcatcher (2014), American Sniper (2014), and The Loudest Voice (2019 miniseries), showcasing her versatility across drama, action, and television.