The Flood are fictional parasitic alien life forms in the Halo video game series created by Bungie. They are introduced in as a second enemy faction alongside the Covenant, and return in sequels Halo 2, Halo 3, Halo Wars and as a gametype in Halo 4. The Flood are driven by a desire to infect any sentient life they encounter, and are depicted as such a threat that the ancient Forerunners were forced to kill themselves and all other sentient life nearly 100,000 years ago in an effort to starve the Flood to death.