Sienna Miller Birthdate: December 28, 1981 Place of Birth: New York, NY Significant Other: Caused a stir when it was discovered she's dating her "Alfie" co-star, Jude Law. Sienna Miller Biography (Courtesy of Paramount and "Alfie"): November 3, 2004 - Sienna Miller ('Nikki' in "Alfie") was born in New York and educated at Heathfield School in Berkshire. She studied drama at the Lee Strasberg Institute in New York. In the millennium, Sienna Miller starred in the off-Broadway production o