Cortana is a fictional
synthetic intelligence character in the
Halo video game series. Voiced by
Jen Taylor, she appears in and its sequels,
Halo 2,
Halo 3,
Halo 4 and
Halo 5: Guardians. She also appears in a cutscene and the epilogue of the prequel , as well as in several of the franchise's novels and comics. During gameplay, Cortana provides backstory and tactical information to the player, who assumes the role of
Master Chief Petty Officer John-117. In the story, she is instrumental in preventing the activation of the
Halo installations, which would have destroyed all
sentient life in the galaxy.