Keeper of the Matrix



The position of Keeper of the Matrix was given to the Time Lord that watched over the Matrix and was in full charge of it. The Keeper had the Key of Rassilon, the only key to the Matrix, on his person at all time and if anything should happen to the Matrix, the Keeper was to repair it and make any necessary adjustments.

At the conclusion of the Sixth Doctor's trial, the Keeper had been taken over by the Valeyard. Possibly the real Keeper never left Gallifrey.(DW: The Trial of a Time Lord - The Ultimate Foe)

The position replaced that of Co-ordinator when Lord President Niroc was elected. (EDA: The Eight Doctors)