An extragalactic species from Warhammer 40K named for the first human world in the Milky Way devoured by them. The Tyranids are a spacefaring ecosystem organized into "Hive Fleets" that travel from planet to planet. Upon discovery of a planet with sufficient biomass, the Tyranids launch an unrelenting invasion, utilizing extensive and highly-adaptable combat forms, their powerful hive mind, and psychic abilities to devastate its defenders and isolate it from the greater galaxy, before ultimately leaving it a lifeless husk.
