Mindcore

The Mindcore served as the collection of the Skith race's greatest minds and the sum of all Skith knowledge. A copy was installed on all Skith starships and was used to advise and supervise the commanders and their subordinates. The Mindcore  itself was located around the ship's fusion core, and appeared as a huge column of light with a series of disembodied heads. (DWM: The First, The Age of Ice)

While the Mindcore copies in the Skith ships operated independently, they maintained constant contact with the main Mindcore on the Skith Ownworld.

History
The Skith ship Oppressor One landed in Antarctica in 1915, planning to experiment on the fauna there before cataloguing and obliterating the planet. While there they found the Antarctic Expedition of Ernest Shackleton and the Tenth Doctor. The Mindcore declared the mission a failure, since the Doctor's presence indicated the planet had been tampered with. The Doctor infiltrated the Mindcore shortly after, and destroyed the Oppressor One. (DWM: The First)

A mysterious force destroyed the Skith Ownworld, causing the Mindcore of the Oppressor Two to hunt for the Doctor so it could develop time travel to combat the force. The Oppressor Two showed up above Sydney, Australia in 2010 and successfully captured the Doctor and Majenta Pryce, but a conflict between the Skith Leader of Oppressor One and the Skith General of Oppressor Two allowed the Doctor and UNIT to destroy the ship. (DWM: The Age of Ice)