Sentilli

Sentilli was a black hole found in the Andromeda Galaxy.

History
At some point in the black hole’s history, the Cult of Shining Darkness placed a colossal space station known as ‘the Torch’ into the black hole. The station had a very powerful shielding and so remained intact.

Much later, a faction of the Cult arrived in the Sentilli System with a device that would open the black hole and allow the station out. They intended to use the station to control all the robotic life forms in the Andromeda Galaxy. They could then use the robots as an army to enforce their view of the supremacy of organic beings over non-organic life. However, the Doctor and Donna as well as the crew of the Sword of Justice defeated the Cult and sent the station back into the black hole with its shields down, so it would have been destroyed. (NSA: Shining Darkness)