[Name] Flood Parasite [Source] Halo [Symptoms] 
The Flood Parasite is depicted in the Halo franchise as a parasitoid fungus-like pathogen that mutates infected hosts into creatures similar to zombies. Depending on the size or condition of the Host's body, the Flood will either uses the host as-is to pursue new victims, or break it down to create "pure forms" from its biomass.