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 Cyber-tombs, sealing the Cybermen in. (TV: The Tomb of the Cybermen)

Notes

Toberman was intended to be deaf, but there appear to be no reference to this in the episode. However, the references did make it into the episode novelization.