Mavic Chen
Mavic Chen was the Guardian of the Solar System around the turn of the 41st century and betrayer of the solar system to the Daleks.
Biography
As Guardian of the Solar System, Mavic Chen ruled over Earth and her dominions. The influence of this power bloc extended far beyond it's political boundaries, but even so Chen craved even greater power. He was involved in the Non-Aggression Pact of 3975. 25 years later, corrupted by a lust for power, Chen willingly betrayed his own people and joined an alliance with the Daleks and the Outer Galaxies, who plotted to conquer the Solar System, and granted the Daleks the taranium they would need to complete their Time Destructor. (DW: Mission to the Unknown, The Daleks' Master Plan) However to Chen this alliance was merely a tool; a stepping stone on his inevitable rise to greatness and immortality as 'First Ruler of the Universe'. He travelled in his space vessel, 1-11 Spar, to join the seventh meeting of the Galactic Council, meanwhile plotting to send a force from Venus to destroy Kembel, and the delegates, after he had gained the Time Destructor.
When the Doctor and his companions succeeded in stealing the taranium from the Daleks' base on Kembel, Chen at first recruited Space Security Service agent Sara Kingdom to help him. Chen had lied, telling her that her brother Bret Vyon, who was helping the Doctor, was a traitor. Sara believed Chen and killed her brother, but switched over to the Doctor's side upon learning the truth.
When the Doctor attempted to elude his enemies in his TARDIS, Chen joined the Daleks in their pursuit of them through the centuries. Chen was able to retrieve the taranium after the Daleks caught up with the Doctor in ancient Egypt. Chen and his allies returned to Kembel, where he convinced himself that he was the equal of the Daleks and when the other members challenged him he killed Gearon, telling the remaining delegates they would be allowed to govern their galaxies, directly responsible to the Dalek Supreme and himself. The Daleks pretended to go along with his plans but imprisoned him along with the others, leading them to propose a new Alliance against the Daleks. On his release he destroyed his ship in order to fake his death and took Steven and Sara to the Daleks underground base in order to rebuild his alliance. He attempted to give orders to the Daleks but, having served out his usefulness, and tiring of him, he was finally exterminated by the Daleks. By now insane, Chen proclaimed he was immortal even as the Daleks' gunsticks fired upon him. The Daleks soon followed him in death, as the Doctor activated the Time Destructor himself and destroyed all life on Kembel. (DW: The Daleks' Master Plan)
Chen's Legacy
Despite Chen's betrayal of Earth and his extermination by the Daleks, he succeeded in founding a dynasty that controlled Earth and much of the galaxy for many centuries.