Cortana (Earth-5875)

Cortana (serial number: CTN452-9) was an Auton synthetic who served the UNSC during the last years of the First Contact War, Cortana was the brainchild of Dr. Catherine Halsey, one of humanity's greatest minds and one of the UNSC's greatest assets, in order to serve as a tactical companion for SPARTAN-II Blue Team for Operation RED FLAG.