Serena Kogan is a minor character from Terminator: Salvation who is portrayed by Helena Bonham Carter. She appears in the film's prologue as a genetic/cybernetic specialist working for Cyberdyne Systems and she is also a terminally-ill cancer patient. During the prologue, she meets Marcus Wright in prison on the day of his execution, requesting that he sign over his body to Cyberdyne for experimentation. She and Marcus share a kiss in his cell and he signs her documents, and later she witnesses his lethal injection.
That is all that is seen of Kogan, who dies off-screen presumably of her cancer. Much later in the film, Marcus enters Skynet Central in San Francisco where Skynet communicates with him directly, using Kogan's face as a digital avatar that Marcus would be familiar with.