One sister, Savannah, two half-brothers, Charles and Stephen and a step-sister, Natasha.

Her mother, Jo Miller, ran London's Lee Strasberg drama school.

Studied drama at the Lee Strasberg Institute in New York.

For more than a decade her father, American Banker Ed Miller, was married to top interior designer Kelly Hoppen.

Was educated at Heathfield School in Ascot, Berkshire.

Her birthday is one day before that of ex-boyfriend Jude Law.

She was born in the USA but raised in the UK.

Met boyfriend Jude Law when they made the movie Alfie (2004) together.

Named her two dogs Porgy and Bess after the two leading characters in Gershwin's opera of the same name.

Became engaged to Jude Law on Christmas Day, 2004.

Studied acting with Michael Margotta.

Jude Law publicly apologized for cheating on her with nanny Daisy Wright. [July 2005]

In the summer of 2005, she made her West End debut in the stage production of William Shakespeare's "As You Like It", directed by David Lan, at the Wyndham Theatre. She played the role of Celia.

Ended her seven-month engagement with Jude Law. [Late July 2005]

Her sister celebrates her birthday two days after Sienna's.

Named #48 on the Maxim magazine Hot 100 of 2005 list.

Named #2 in AskMen.com's Top 99 Most Desirable Women

Ranked and Voted #2 by AskMen.com's Top 99 Most Desirable Women of 2006

Friend of Keira Knightley.

She and co-star Hayden Christensen shared a house during the filming of Factory Girl (2006) in Louisiana.

#42 on maxims hot 100 of 2006

Lost out on the role of "Lureen Twist" in Brokeback Mountain (2005) to Anne Hathaway.

Named #63 in FHM magazine's "100 Sexiest Women in the World 2006" supplement. (2006).

Broke up with Jude Law, again [November 13, 2006].

Fan of Chelsea FC (England football club).

Told "The Daily Telegraph" newspaper in February 2007 that she has tried to quit smoking, but "it's so hard.".

Replaced Lindsay Lohan for the role of Caitlin MacNamarra in The Edge of Love (2008) starring alongside her close friend Keira Knightley.

Ranked #11 on the Maxim magazine Hot 100 of 2007 list.

Was named "Film Actress of the Year" at the 2007 Glamour Women Of The Year Awards.