Sty

Colonel Sty of the Bolkon Context was a member of the Endangered Dangerous Species Society. He was a powerful being with thick, rubbery skin. He relied on the most advanced weaponry he could find, but he still could and would use his Krat dagger in close combat.

Based on his name and description, Colonel Sty may have been a Sontaran.

Colonel Sty was brought to Planet 1 by Sebastiene in order to hunt the Doctor. Though a section of the planet had been recreated in the form of the Bolkon Context, he didn't get a chance to hunt the Doctor there. Instead, he was taken from there to another section of the planet. He was eventually killed by Zzorg Zero so that he would have less competition. (TDA: The Doctor Trap)