The Sycorax Leader was the leader of a tribe of Sycorax. He led an asteroid ship to Earth in 2006. They tried to invade the planet using blood control.

In 2006 he led the tribe into Earth's airspace above London, specifically Powell Estate. He saw through Rose Tyler's subterfuge when she claimed to have the authority to order the invaders to depart.

He duelled with the newly-regenerated Tenth Doctor and cut off his hand which, owing to the after-effects of regeneration, grew back. This allowed the Doctor to defeat him. When the Doctor's back was turned, the leader tried 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. The Doctor justified his action by stating, "No second chances. I'm that sort of man."

The Great Intelligence mentioned, among others, the death of "the leader of the Sycorax" at the hands of the Doctor to dispute Madame Vastra's claim that the Doctor was never "blood-soaked".

_{Biography from the TARDIS Data Core article, licensed under CC-BY-SA}