Brains

Brains was one of the punishment platoon on Hedgewick's World of Wonders. When Clara Oswald took command of the platoon, he asked her to sign for the trigger to the planet-imploding bomb. He was almost upgraded by the Cybermen, but the Eleventh Doctor, whose mind was partially taken over by Mr Clever, pulled in the resources to decide a chess move against Clever, stopping the Cybermen. (TV: Nightmare in Silver)