Partheus

Partheus was the Time Lord entrusted by Rassilon to deploy the Tear of Isha into the Tantalus Eye during the Last Great Time War. The War Doctor parked his TARDIS into Partheus' TARDIS to prevent Partheus from deploying the Tear.

The Doctor hijacked Partheus' TARDIS and sent it to the end of the universe, where Cinder hit the button which sent the Tear into a red giant, preventing the Time Lords from committing genocide against the inhabitants of the Tantalus Spiral. Partheus pointed his gun at the Doctor, but the Doctor talked him down from firing. Partheus then demanded the Doctor and Cinder to leave the ship. (PROSE: Engines of War)