The Sycorax
The Sycorax first appeared in The Christmas Invasion (2005 Christmas Special) just after the Doctor regenerated from his Ninth incarnation to his Tenth. The Sycorax are humanoid beings with both endoskeletons and exoskeletons. Their heads are part bone like structure with exposed muscle, though the exoskeleton part could vary between each member of the Sycorax species. The Sycorax divided into large tribes that made up the Sycorax Empire, and had some respect for the laws of combat. Leadership of a Sycorax tribe was decided by trials of strength and combat. The Sycorax also wore skeletal helmets to impress or scare their enemies as well as red robes to indicate authority and leadership. If the Sycorax conquered another race, they would take body parts of that race, such as skin or hair.
The Sycorax were big on the use of slavery in their missions, and attempted to enslave the humans. The Sycorax threatened the humans by using blood taken from the spacecraft Guinevere One to cause one third of the population to prepare to jump from high buildings if they did not get half the population as slaves. The Sycorax believed in magic and witchcraft, of which their blood control was likened to by the Doctor. The Doctor stopped this plan by activating the command to make the humans jump, but they couldn’t as their survival instinct was stronger than the control the Sycorax had over them. The Doctor challenged the Sycorax leader to a fight for Earth, which the Sycorax leader lost, but weren’t willing to let the Doctor win easily, the leader attempted to kill the Doctor from behind, but the Doctor was ready for him and beat him, making him fall from the spaceship to Earth. As the Doctor has beaten the Sycorax leader, the rest agreed to leave Earth well alone. However, as they were leaving, Harriet Jones ordered Torchwood to shoot the ship out of the sky, killing the remaining Sycorax on board. The Sycorax were also among the enemies of the Doctor seen at the Pandorica in The Pandorica Opens (Series 5 : Episode 12) as part of the alliance.