Halo: Combat Evolved

 The Flood is a fictional parasitic alien life form. Flood-infected creatures, also called Flood, in turn infect other sentient hosts. They were introduced as a second enemy faction in the 2001 video game Halo: Combat Evolved, the first game in Bungie's Halo multimedia franchise. Their design and fiction was spearheaded by Bungie artist Robert McLees, with sound design led by Martin O'Donnell. The ringworld setting of the first Halo game was stripped of many of its large creatures for Halo 2 to make the Flood's surprise appearance more startling. For Halo 3, Bungie environment artist Vic DeLeon spent six months of pre-production time refining their fleshy aesthetic and designing the organic interiors of Flood-infested space ships. Reaction to the Flood has varied; while some reviewers found the creatures too derivative and a cliché element of science fiction, others ranked them among the greatest video game villains of all time.