Omnethoth

The Omnethoth was a sentient weapons system designed by a race called the Masters, who created it with universal domination in mind.

History
The Euterpians and Greld used the Omnethoth during the Millennium War. (PDA: The Quantum Archangel)

The Omnethoth eventually destroyed the Masters and then found its way to the Minerva system, where it totally destroyed Yquatine. The Doctor reprogrammed the Omenthoth to make them tame and harmless, after which President Vargeld of Yquatine had them destroyed. (EDA: The Fall of Yquatine)