Claire Redfield is the younger sister of former S.T.A.R.S. member Chris Redfield. She first appeared in Resident Evil 2, and has by far appeared in 3 games, 1 CG film, and 2 live action films, but hasn't appeared in a brand new "over-the-shoulder" Resident Evil game. Claire is an avid motorcyclist, and a member of Terra Save. She was present in Raccoon City during the t-virus outbreak.
Throughout the series, Claire showed signs of emotions either concealed or nonexistent in most of the characters in the series. Thus, she is often considered as the most emotional character by fans. Claire also develops very close relationships to other characters like Leon, Steve, Sherry, and Rani to name a few. But the closest relationship she has is with her brother Chris, as shown in CODE: Veronica.
However, in Resident Evil: Extinction, her personality seems a lot different than her video game counterpart. She appears as somewhat arrogant, but acts like a leader. One similarity to her video game counterpart is that Claire also takes on a sisterly role to many of the younger survivors (in particular, K-mart, who is commonly found in her company).