CyberMaster

From Tardis Wiki, the free Doctor Who reference

For the title briefly adopted by the War Master, see Cyber-Master .

The CyberMasters were Cyber-converted Time Lords created by the Spy Master from the corpses of all those who had been on Gallifrey when he destroyed the Capitol. They retained the ability to regenerate which made them effectively invincible. The CyberMasters were apparently destroyed when Ko Sharmus detonated the death particle, obliterating all organic life on Gallifrey. (TV: The Timeless Children)