Dark Matrix
From Tardis Wiki, the free Doctor Who reference
The legendary Dark Matrix was a repository of all the dead Time Lords' most evil, twisted and perverted thoughts. It was the antithesis of the Matrix. The Doctor confronted the Dark Matrix when the Valeyard - attempting to use its power to give himself a new body - had trapped it inside his TARDIS, provoking the Dark Matrix into destroying the TARDIS and itself when the Doctor convinced it that it was still a prisoner. (PDA: Matrix)
