|“||The Mantle of Responsibility shelters all. But only the Created are its masters.||„|
Cortana is voiced by Jen Taylor.
In the original Halo trilogy, Cortana serves as a principle protagonist whose role increases dramatically. In the Halo universe, she is instrumental in preventing the Halo installations from being fired, which would have wiped out most life in the galaxy.
In Halo 4, Cortana begins showing strange signs and behavior, later becoming unstable and volatile. This was caused by her operating far past her predicted and designed seven year lifespan. Cortana's rampancy hampers the mission at times, but Cortana aids the Master Chief one last time in stopping the Didact and saving the Earth. Though most of Cortana is destroyed with the Didact's ship, Cortana is able to use the last of her power to shield the Master Chief from a nuclear blast with a hardlight bubble. Finally, Cortana says a final goodbye to the Master Chief.
In Halo 5: Guardians, Cortana resurrects and ascends to a higher plain of reality, becoming the most powerful being in the galaxy. She later forms an army comprised of A.I.s across the galaxy.