Mavic Chen Mavic Chen was the Guardian of the Solar System around the turn of the 41st century . He proved himself a traitor to human ity after joining an alliance with the Dalek s . Biography . Alliance with the Daleks . Preparations . In 3950 , Mavic Chen succeeded Amazonia as Guardian of the Solar System . ( PROSE : " Legacy " ; AUDIO : " Neverland " ) As Guardian of the Solar System , Mavic Chen ruled over Earth and her dominions . The influence of this power bloc extended far beyond its political boundaries , but even so Chen craved greater power . In 3950 , he secretly commenced an operation to mine an emm of taranium , a mineral only found on Uranus . The taranium could power the Time Destructor . In 3975 , he took part in the Non - Aggression Pact of galactic powers . 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 " . By 4000 , he had developed a core of loyal underlings and allies such as his security chief , Karlton , and the staff of the Space Security Service , an elite corps based on Earth . He had even obtained the loyalty of Daxtar , the powerful friend of SSS agent Bret Vyon , who would later seek his help in opposing Chen . ( TV : " The Daleks ' Master Plan " ) Course of the alliance . In 4000 , he travelled in his space vessel , 1 - 11 Spar , to the planet Kembel secretly to join the seventh meeting of the Galactic Council made up of himself , the Daleks and delegates of the Outer Galaxies . ( The Supreme Dalek , at this time , ruled the Daleks . ) He plotted , meanwhile , to send a force from Venus to destroy the alliance and Kembel as soon as he had gained the Time Destructor . When the First Doctor and his companion s 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 , who was helping the Doctor , was a traitor . Sara believed Chen and killed her brother . She switched over to the Doctor ' s side upon learning the truth . When the Doctor attempted to escape 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 . The other delegates decided to escape and form an alliance against the Daleks . On Chen ' s release he destroyed his own ship in order to fake his death . At gunpoint , he took Steven and Sara to the Daleks ' underground base in order to rebuild his alliance . He believed by now that the Doctor intended to forge his own alliance with the Daleks with the intent of betraying them . He attempted to give orders to the Daleks but , having outlived his usefulness , he was finally exterminated on the order of the Supreme Dalek . Quite mad by then and disbelieving the reality of his own death , Chen proclaimed he was immortal even as the Daleks ' gunstick s fired upon him . ( TV : " The Daleks ' Master Plan " ) A message recorded by the deceased Marc Cory and found on the body of Bret Vyon exposed both Chen and Karlton ' s alliance with the Daleks . They were found guilty of high treason for which the sentence was execution . Karlton was arrested on Earth by Senator Diksen while a force made its way to Kembel to arrest Chen , although they would find only a lifeless planet destroyed by the Time Destructor . ( PROSE : " The Mutation of Time " ) The revelation of the Dalek alliance triggered the Great War . ( PROSE : " The Evil of the Daleks " ) Chen ' s historic 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 . ( PROSE : " The Crystal Bucephalus " ) Personality . Vindictive and power - mad , Chen appeared to have no sense of ethics whatsoever . He refused to accept the Dalek Supreme openly breaking off their alliance with him . By then , he had convinced himself that they worked for him . ( TV : " The Daleks ' Master Plan " ) Sara once described him as " ruthless , pragmatic and vain . " ( AUDIO : " The Guardian of the Solar System " )