The Extortioner

The Extortioner was a criminal who set up a base inside a volcano on an unnamed planet. After capturing the Second Doctor, he contacted the governments of all the inhabited planets in the universe and threatened to destroy their cities with his missiles if he was not given all of their valuables. The Doctor escaped and defeated the Extortioner's plans by dropping his missiles' warheads into the volcano's core, causing it to erupt and destroy his base. Enraged, the Extortioner pursued the Doctor in his giant mechanical mole, but the Doctor lured him to a crack in the ground created by the eruption and he fell to his death. (TVC: The Extortioner)