Tyranids

The Tyranids, also known as The Great Devourer are an extragalactic alien race, whose sole purpose is the consumption of all forms of genetic and biological material in order to evolve and reproduce. Tyranid technology is based entirely on biological engineering. Every function is carried out by living, engineered creatures, each of which collectively forms the Hive Fleet, directed by a single Hive Mind.

The Tyranids are seen as one of the gravest threats to the entire Galaxy. They seek only to consume all organic life and cannot be reasoned with or deterred in this quest. Worse still for the Galaxy, thus far the Tyranid Hive Fleets that have been encountered are merely the furthest stretched tendril of the main invasion fleet that is still traveling in the void of space