Toberman

Toberman was Kaftan's servant. He accompanied her on Professor Parry's expedition to Telos. He was captured by the Cybermen, partially cyberconverted and placed under their control. When the Cyber-Controller killed Kaftan,Toberman regained his humanity and attacked the Controller. He sacrificed his life to close the electrified doors of the Cybermen's tombs, thus sealing them in. (DW: The Tomb of the Cybermen)