First Elder (The Sensorites)
The First Elder was the leader of the Sensorites, in the 28th century. The First Elder was on the Sense Sphere when an Earth ship landed on his world, containing five humans. The humans had come to the Sense Sphere hoping to mine for the valuable element, molybdenum. Unfortunately, the Sensorites' telepathy drove three of the humans insane, causing them to believe that they were at war with the Sensorites. When the other two Humans tried to leave the planet, the remaining humans blew up their own ship. The First Elder believed that all five humans had died in the explosion. However, the surviving humans poisoned the Sensorites' aqueducts, killing three in every ten Sensorites. The First Elder believed that the humans had carried a disease with them, and forbade any more humans from coming to the Sense Sphere. Years later, another Earth ship, commanded by Captain Maitland approached the Sense Sphere. The First Elder ordered that the humans be kept prisoners on their ship, which was forced to remain in orbit. When the Doctor's TARDIS landed on the Earth ship, the Sensorites detected that Susan, a young Time Lady had telepathic abilities. He asked that Susan be brought to the surface, but the Doctor refused to allow Susan to go unless accompanied by himself and Ian Chesterton. Two members of the ships crew, Carol Richmond and her fiancé, John, who had been driven insane by the Sensorites, we're allowed to join them. When they arrived on the Sense Sphere, the First Elder met with the Doctor and his two companions. He explained the situation to the Doctor, who agreed to help him find a cure to the disease. After Chesterton became ill, shortly after drinking water from the aqueducts, the Doctor surmised that the water was poison. Upon consulting with his suspicious Second Elder, the First Elder chose not to let the Doctor have access to his TARIS, but agreed to allow him access to a lab on the Sense Sphere. The Doctor found a cure for the poison, but it was intercepted by the City Administrator. The First Elder began to trust the Doctor after he cured the Sensorites, but the Coty Administrator did not share this trust. He murdered the Second Elder, and unsuccesfully framed the Doctor. Following the Doctor's advice, the City Administrator was promoted to Second Elder. After the three humans were found by the Doctor in the aquaducts, the First Administrator allowed Captain Maitland to return to Earth with them. He also, somehow, found out that his new Second Elder was a traitor and had him banished.
