Sarah Connor is tough and strong-willed, Sarah Connor is the mother of John Connor, who will supposedly lead a resistance against machine conquest after the apocalypse known as Judgment Day. Her love for her son is absolute, and she will stop at nothing to protect him and help ensure the survival of the human race. The authorities, however, see her as a deranged fugitive.

Series creator Josh Friedman saw over 300 actresses for the role and described the actress he was looking for was someone "who embodied that spirit and who was believable in that role and not just some glammed up, Hollywood, actressy thing". After a friend recommended English actress 'Lena Headey' for the role, Friedman watched her audition tape, and thought she was "a tough, tough woman". Having seen The Terminator when she was a teenager, which "scared the hell out of her," Headey was aware of the iconic status of the character and in regards to Linda Hamilton's portrayal of the role in the film series, she remarked, "Linda Hamilton will always be the original Sarah Connor and it's a very strong print that she's left, but hopefully people will embrace what I bring to Sarah and see it with fresh eyes".

When asked about her approach to the role, Headey said "I'm playing a mother who is a single parent, bringing up a teenage son, who also happens to save the world — as a byline to her life. And the way I would play that is someone who's passionate and scared and angry and a mother, all these things. So I approach that just trying to be honest within the boundaries of her". However, the choice to cast Headey was criticized by several fans and critics who argued that she bore no resemblance to the athletic, muscular woman established by Hamilton, who transformed her body into that of a muscled warrior for Terminator 2.