Claire Redfield is the sister of Chris Redfield, a member of the Special Tactics And Rescue Service (S.T.A.R.S.) team who had gone missing. Claire, a college student and sometime motorcyclist, arrived in Raccoon City to try and discover what had happened to her brother, only to find herself caught up in the middle of a zombie holocaust.
While battling the zombie infestation, Claire learned that her brother had previously left the country for Europe in order to investigate the Umbrella Corporation, the company that was responsible for creating the T-Virus, a biological weapon that was accidentally unleashed on the world and was the cause of the zombie outbreak. Realizing that her brother was safe for now, Claire turned her attention towards getting out of the city in one piece.
She did eventually make it out and followed her brother to Europe, where she was captured and incarcerated by Umbrella's operatives on Rockfort Island. Claire eventually managed to escape along with her fellow prisoner Steve Burnside, but the two soon wound up in an Umbrella secret laboratory in Antarctica where they were captured yet again. Eventually Chris discovered his sister and saved her, and the two continue to battle against the evil Umbrella Corporation to this day.
In the film version of the Resident Evil saga, or what could be considered an alternate timeline from the games, Claire and Carlos Oliveira were the leaders of a convoy of plague survivors traveling from the Nevada desert to Alaska. They joined together with the T-Virus superhuman Alice in their struggle against Umbrella, and eventually Claire and a handful of convoy survivors were believed to have made it to Alaska where they could live in relative peace and safety. Claire is having a reappearances in Resident Evil Afterlife counting from the third film