Sycorax leader
The Sycorax leader was a high-ranking Sycorax and led the massive asteroid ship to Earth where they tried to invade it using blood control. The leader saw through Rose Tyler's subterfuge when she claimed to have the authority to turn back the invaders.
Atop the hull of the ship, now hovering in the airspace above the Powell Estate, London, the leader dueled with the newly-regenerated Doctor and was eventually defeated by him. When the Doctor's back was turned, the leader tried again to kill him again but the Doctor used a satsuma from his borrowed dressing gown to hit a button which sent the leader falling to his death. (DW: The Christmas Invasion)