The Master

Home Planet: Utopia
Life Form: Spherical Human-Based Cyborgs

During the Last Great Time War, the Master cowardly escaped, and hid himself as a human at the end of the universe, using a chameleon arch, containing his true form into a small fob watch. His human form was in the shape of a kindly Professor Yana, with his assistant, Chantho. They were trying to come up with a way for the humans on Malcassairo to escape to Utopia. But when the Doctor arrived, the Professor started to act strangely. Being drawn towards the fob watch, he opened it, and turned into his true form. He stole the Doctor’s Tardis, just after Chantho shot him, before whe, too, died, and he regenerated. He went to Utopia, and saw what the humans had become, and so promised them the Earth. He came to early 21st century Britain, where he called himself Harold Saxon and successfully ran for the position of Prime Minister. This was achieved through the Archangel Network in the form of a subtle mind manipulation system that rang the drumming beat the Master heard in his head into the subconscious of every person on the planet, giving him the trust of the world. He faked a first contact with the Toclafane, what the humans had become in Utopia. Using the TARDIS, the Master built a paradox machine to facilitate the Toclafane Invasion. The Master used a Laser screwdriver to turn the Doctor into an elderly man, capturing both him and Jack Harkness though Martha Jones escaped. A year later, the Master was planning to unleash the Toclafane upon the universe using a countdown through the Archangel Network. However, the return of Martha Jones threatened his plans. He captured her, but Martha had told the world of the Doctor and to think his name at the end of Archangel's countdown, which the Doctor has spent the year telepathically infiltrating while the Master's prisoner. This empowered the Doctor massively and led to the Master's plans being foiled as Jack Harkness destroyed the paradox machine, reversing time back to the point of the takeover of Earth, undoing most of the Master's destruction in "The Year That Never Was".

Episodes: Utopia, The Sound of Drums, Last of the Timelords