Master Chief (Halo)
MCPON John-117, or "Master Chief", is a fictional character and the protagonist of the "Halo" fictional universe created by Bungie. Master Chief is a playable character in the series of science fiction first-person shooter video games "", "Halo 2", "Halo 3", "Halo 4", and "". Outside video games, the character appears in books and graphic novels—"", "", "", and ""—and has cameos in other "Halo" media, including "", "", "The Halo Graphic Novel", "Halo Legends" and "".
Cortana (Halo)
In "Halo 2", a Covenant fleet arrives above Earth, and Cortana takes control of an orbital coilgun to repel the invaders. Cortana, Chief and human forces travel to another Halo ring, Delta Halo, where Master Chief and Cortana encounter the Flood intelligence Gravemind. The Gravemind sends Chief and Cortana to the Covenant city-ship of "High Charity" to stop the Covenant from activating Halo; Cortana infiltrates "High Charity"s computer systems to assist Chief, ultimately staying behind to destroy the city and Halo should Master Chief fail in his mission to stop the Covenant leadership. "High Charity" is assimilated by the Flood, and Cortana is left behind.