Flood - Species - Halopedia, the Halo wiki

The Flood, designated as LF.Xx.3273 by the Forerunners and referred to as the Parasite and the infection by the Covenant, is a species of highly virulent parasitic organisms that reproduce and grow by consuming sentient lifeforms of sufficient

Halo 4 - Wikipedia

Precursor (Halo), Alien Species

Earth, Halo Alpha

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List of unidentified species - Halopedia, the Halo wiki