Thanatos (weapon)

The Thanatos, also known as the World Bane, was a machine noted as the greatest superweapon ever created.

Powers
The Thanatos was a weapon capable of destroying whole planets. It could probe people with tentacles that interfaced with the individual on a mental and physical level. A judgment engine inside the machine decided whether to exterminate a race. It determined whether a species was at an evolutionary dead end. It produced the Inuk to serve as its antibodies and was intelligent enough to herd enemies into traps. (DWM: The Betrothal of Sontar)

History
The Sontaran Colonel Snathe searched for the weapon to return glory to his name. He was looking for it on the planet Serac with the Betrothal of Sontar. After encountering The Doctor, he claimed he would help the Sontaran find the machine.

They found the Thanatos under the ice, where it was guarded by the transformed Inuk. They destroyed his aircraft, but the Doctor reprogrammed a drone and used it to escape -- they believed. They were just being chased deeper in the Thanatos. Rose Tyler and Lerox caught up with the Doctor and Snathe, just when Snathe began to interface with the Thanatos. Unfortunately, Thanatos judged that the Sontarans were a stagnant race and Sontar needed to be destroyed. Lerox was shown to be capable of self-sacrifice, so the Sontarans were spared, but Snathe was ejected from the Thanatos during the middle of a Silverfire, killing him. (DWM: The Betrothal of Sontar)