In the
X-Box game
Halo: Combat Evolved, Cortana is the
AI entity that's contained within
Master Chief's
armor.
Created after the
likeness of her
creator, in
Halo's
universe, Cortana is the single most
advanced AI known to man.
When the
Pillar of Autumn is about to crash on the
Halo Ringworld,
Cortana is transferred to the Master Chief to live up to the
Cole Protocol.