Despite not having any lines in the pilot, Sansa does make an appearance so they will need to cast the part with the expectation that she will later play a major role. It is conceivable that they could cast a stand-in then recast and reshoot the few scenes she is in if the series gets picked up, but it is more likely that they will just go ahead and cast the role from the beginning to avoid having to do any reshoots. Here are a few actresses that may be considered for the role.
Rachel Hurd-Wood – The hands-down consensus choice, Hurd-Wood had her breakout role as Wendy in the live action Peter Pan film. She has since done a few other smaller films. She certainly has the look, no hair dye needed here. Also judging by her credit list, it seems the Brit has a fondness for costume dramas. The big thing working against her is her age. By the time they start filming she will be 19 years old and I don’t think she can pass for a 13 year old girl now.
Julia Winter – The next candidate is much closer to Sansa’s age in the pilot script. Winter, who was born in Swedish but raised in London, will be 16 by the time filming begins. Her first (and only role so far) was as Veruca Salt in the Tim Burton film, Charlie and the Chocolate Factory. While she is the right age and has a decent-enough look (not to mention the perfect last name!), her relative inexperience may hurt her here.
Dakota Blue Richards – Another young actress who was plucked from obscurity to star in a major film, Richards won the role of Lyra in The Golden Compass via an open audition that attracted 10,000 other hopefuls. Unlike Winter, Richards has followed up that opportunity with a few other movie roles. At 15 she would be the right age and she has the right look. It looks like sequels for The Golden Compass are on hold for now. So she should have the availability as well.
Lucy Boynton – Lastly, we have Boynton. While not in any films as large as the above three, her first role was as Young Beatrix Potter in Miss Potter. She has followed that up with two roles in BBC productions, the made-for-TV movie Ballet Shoes and the Sense and Sensibility mini-series. The London-born actress would be 15 at the time of filming, so she is in the correct age range. Also having worked with the BBC might help her chances. Right age, right look, right price… right choice?
As I mentioned, it wouldn’t be too surprising for Benioff and Weiss to not officially cast this role unless the series gets picked up. To avoid having to do reshoots, they could even write Sansa out of the script. Just introduce her character officially in the second episode. This might be the best solution to avoid having to spend a lot of time to cast a character that is only going to stand around in the background for the pilot episode. We shall see what they do.