Summer Glau (born July 24, 1981) is an American actress best known for her roles in science fiction and fantasy television series; as River Tam in Firefly (2002) and its continuation film Serenity (2005), as Tess Doerner in The 4400 (2005–2007), as Cameron / Allison Young in Terminator: The Sarah Connor Chronicles (2008–2009), as Bennett Halverson in Dollhouse (2009–2010), as Skylar Adams in Alphas (2011–2012) and as Isabel Rochev / Ravager in Arrow (2013–2014).