
Sienna Rosie Diana Miller (born December 28, 1981) is an American-born English actress. Born in New York City and raised in London, she began her career as a photography model, appearing in the pages of Italian Vogue and for the 2003 Pirelli calendar. Her acting breakthrough came in the 2004 films Layer Cake and Alfie. She subsequently portrayed socialite Edie Sedgwick in Factory Girl (2006) and author Caitlin Macnamara in The Edge of Love (2008), and was nominated for the 2008 BAFTA Rising Star Award. Her role as The Baroness in G.I. Joe: The Rise of Cobra (2009) was followed by a brief sabbatical from the screen amid increased tabloid scrutiny.
Miller returned to prominence with her role as actress Tippi Hedren in the television film The Girl (2012), for which she was nominated for the BAFTA Television Award for Best Actress and the Golden Globe Award for Best Actress – Miniseries or Television Film. Further critical acclaim followed throughout the 2010s, with appearances in the films Foxcatcher (2014), American Sniper (2014), Mississippi Grind (2015), The Lost City of Z (2016), Live by Night (2016), and American Woman (2018), as well as the miniseries The Loudest Voice (2019).

Tom Clancy's Jack Ryan: Ghost War
2026 · as Emma Marlowe

American Sniper
2014 · as Taya Renae Kyle

G.I. Joe: The Rise of Cobra
2009 · as Ana Lewis / Baroness

Stardust
2007 · as Victoria

Horizon: An American Saga - Chapter 1
2024 · as Frances Kittredge

The Lost City of Z
2017 · as Nina Fawcett

Casanova
2005 · as Francesca

Factory Girl
2006 · as Edie Sedgwick

My Mother's Wedding
2025 · as Victoria

Live by Night
2016 · as Emma Gould

21 Bridges
2019 · as Frankie Burns

Burnt
2015 · as Helene

Layer Cake
2004 · as Tammy

Madden
2026 · as Carol Davis

The Girl
2012 · as Tippi Hedren

Wander Darkly
2020 · as Adrienne

Horizon: An American Saga - Chapter 2
2024 · as Frances Kittredge

The Edge of Love
2008 · as Caitlin MacNamara