Matrix Lord

The Matrix Lords were the disembodied minds of deceased Time Lords as they existed within the Matrix. With their mental powers growing to immense length, and further boosted by their Amplified Panatropic Computation Net, they exerted an influence over physical reality greater than they ever had in life, and ruled the living Time Lords from behind the scenes via the Celestial Intervention Agency. (PROSE: The Legacy of Gallifrey)

Some Matrix Lords were the Gallifreyan representatives amongst the High Evolutionaries. The primary Matrix Lords were Rassilon and his two aides, Morvane and Bedevere.

Rassilon declared the "council chamber" of the Matrix Lords and the High Evolutionaries as the home of the Celestial Intervention Agency. (COMIC: The Tides of Time)