Rebecca Nolan was Joshua Nolan's older sister who credited herself with raising him even before their parents died. As a child, young Josh idolized his sister, saying that there "was nothing about her that I didn't want to be." She was originally from St. Louis Missouri where she lived on a suburban street with her family, including Josh and their parents. She had red hair, and liked Johnny Cash and fixing cars.
When the Votan arks arrived, she was more nervous than her younger brother who was excited by their arrival. As Josh watched the arks fly overhead from the window, their house began to shake, and Rebecca saved him from a falling bookcase.
Sometime after the Votans arrived on earth, Joshua Nolan enlisted in the military with romantic notions that it would help make him a man. Rebecca didn't hold the same romantic notions about the war, but she enlisted in the Earth Military Coalition anyway in order to protect her younger brother. While Josh struggled with the violent aspects of the war as a teenager, she didn't share in his struggle. Her parents were vaporized, and at their funerals, she and her family had to bury empty coffins. This motivated her to fight.
During the war, she told Josh that Nolans live or die together, a phrase he would frequently come to use with his daughter, Irisa.
She died after an Irathient soldier convinced Josh to lower his weapon, allowing him the upper hand to shoot Rebecca.
Since her death, Josh has become known as Nolan and has refused to talk about her, never even telling his daughter, Irisa, that he had a sister until she finds out in season 3. She is the only character to routinely call Nolan by his first name, Josh.