The Professor

The Professor was the leader of a gang of criminals who controlled the Underwater Robot. When the First Doctor, John and Gillian were captured and taken to the Professor, he told them how the robot was operated, then had them put to work in the engine room. Instead, they allowed the robot's legs to stop functioning and escaped into the control room, where the Professor tried to kill them with a speargun. The Doctor deflected his aim and the spear shattered a window, flooding the robot and presumably drowning the Professor and his men. (TVC: The Underwater Robot)