Racnoss

The Racnoss are a sapient carnivorous arachnoid species which formed a powerful interstellar empire during the Dark Times of the universe, before being eradicated in a war against the Fledging Empires. They have a hive-like social structure and are lead by a single Empress. These voracious creatures are known to invade whole planets to feed on the inhabitants, and have no concerns whether said inhabitants are sapient.

Biology
The Racnoss appear like massive, red skinned arthropod-like creatures with six pairs of jointed limbs, four to five of which are used for locomotion. Their upper bodies resemble that of a humanoid, making them the vague arachnoid equivalent of a mystical centaur. They have a crested skull and three pairs of eyes, and their mouth is human-looking rather than insectile, but contains razor-sharp white teeth. Their abdomen produces a substance similar to spider silk, which can be used to construct vast webs and immobilize prey.

Technology
The species travel around in star-shaped vessels with hulls made out of their own silk. Racnoss technology used to make heavy use of Huon energy. After their defeat, the Time Lords eliminated all sources of toxic Huon particles in the galaxy, partially to prevent the Racnoss Empire from ever rising again. The last members of the species concealed themselves dormant in a ship hidden at the center of a newly formed planet, which turned out to become Earth. Only the Empress Racnoss remained.

In 2007, a secret drilling operation by the Torchwood Institute accidentally reactivated the Racnoss hidden lair, sending a signal to the Empress to return, so they can rise again and destroy all life on the Earth. They were defeated by the Tenth Doctor, who released the water of the Thames into the Racnoss base to drown them after they refused his offers of peace.