
"Do not underestimate them. And most of all, do not underestimate HIM." - Dr. Halsey
Doctor Catherine Elizabeth Halsey, MD, PhD is a character from the Halo Universe.
She is voiced by Jen Taylor, who also voices Cortana.
Halsey was a praised scientist and former employee turned prisoner of the Office of Naval Intelligence(ONI). She was best known as the creator of the SPARTAN-II Program, the program in which Master Chief Petty Officer John-117 was a part of.
Halsey has feelings of serious guilt for condemning the SPARTANs to only living a life of warfare, and took various measures to protect her remaining SPARTANs, even going against UNSC laws to do just that.
Before being scheduled to be executed, Halsey escaped and defected to the Covenant Remnant.
She was the wife of Captain Jacob Keyes and mother of Maranda Keyes.