- You may be looking for the Garvantine.
Garv was a Keskan slave and a former scientist who the War Doctor met on the Dalek/Taalyen-occupied Keska. He told the Doctor to escape as he knew how to defeat the Daleks. (AUDIO: The Thousand Worlds) He was inside the drill capsule when the Daleks decided to destroy the planets core. He convinced the Doctor to detonate it early so that the Daleks plan would fail. (AUDIO: The Heart of the Battle)