 Jennifer Keller, played by Jewel Staite, is the Chief Medical Officer of the Atlantis expedition, replacing her predecessor, Dr. Carson Beckett (although Keller accepts the role with some reluctance).Graduating high school at the age of 15, Keller was three years ahead of her peers, and earned a bachelor's degree before her 18th birthday.Upon becoming Atlantis' Chief Medical Officer, Keller faces a baptism of fire as she fights to save Dr. Elizabeth Weir who has been badly injured by an Asuran beam weapon.