Sienna and Savannah Miller
Sienna Miller's older sister Savannah isn't quite as famous as the actress, but she has definitely made a name for herself in the fashion world. The 33-year-old, who has worked with both Alexander McQueen and Matthew Williamson, launched an eponymous fashion line in 2012. Sienna, 31, is known for her roles in films such as "G.I. Joe: The Rise of Cobra" and "Factory Girl." —XFINITY Entertainment Staff (Photo by Gareth Cattermole/Getty Images)
The opinions expressed are solely those of the author and do not necessarily reflect the views of Comcast.