Flood (Halo)

The Flood is a fictional parasitic alien lifeform and one of the primary antagonists in the Halo multimedia franchise. First introduced in the 2001 video game Halo: Combat Evolved, it returns in later entries in the series such as Halo 2, Halo 3, and Halo Wars. The Flood is driven by a desire to infect any sentient life of sufficient size; Flood-infected creatures, also called Flood, in turn can infect other hosts. The parasite is depicted as such a threat that the ancient Forerunners constructed artificial ringworld superweapons known as Halos to contain it and, as a last resort, to kill all sentient life in the galaxy in an effort to stop the Flood's spread by starving it.

The Flood's design and fiction were led by Bungie artist Robert McLees, who used unused concepts from the earlier Bungie game Marathon 2. The setting of the first game, the ringworld Halo, was stripped of many of its large creatures in order to make the Flood's surprise appearance more startling. Bungie environment artist Vic DeLeon spent six months of pre-production time refining the Flood's fleshy aesthetic and designing the organic interiors of Flood-infested spaceships for Halo 3.

The player's discovery of the Flood in Halo: Combat Evolved is a major plot twist, and was one of the surprises reviewers noted positively. The Flood's return in Halo 2 and Halo 3 was less enthusiastically praised. Reaction to the Flood has varied. While some critics have described the Flood as derivative or clichéd, others have ranked it among the greatest video game villains.