Deja

Summary
Deja was the "dumb" AI who trained the Spartans in their first stages of training at the CASTLE Base facilities on Reach. She appeared as a Greek goddess, with luminous white hair, barefoot, wrapped in a toga, and holding a clay tablet. Code scrolled across her form at all times.

She was a precursor to Cortana and was used by Dr. Catherine Halsey for various duties. The Spartans thought of her as their teacher, as she trained them in strategy and warfare, whereas Chief Petty Officer Mendez trained them in combat.