Toclafane The Toclafane were the final form of the human race , cyborg s integrated into spherical , mechanical shells . ( TV : " Last of the Time Lords " ) The name " Toclafane " was given to them by , after a fairy tale monster from Gallifrey , the local equivalent of Earth ' s " Boogeyman " . ( TV : " The Sound of Drums " ) Biology . The Toclafane were cyborgs used as the Master ' s brawn and muscle when taking over Earth . They were the heads of humans from the year 100 trillion integrated into a dark - grey sphere - shaped metallic shell , held together with a magnetic clamp . The humans had wiring plugged into their wizened heads . The spheres were very little over a foot tall and were sealed shut . They became a hive mind , allowing them to see the destruction of an individual as no threat . Their personality was amoral and childlike from a failed attempt to regress themselves to children ; instead having rather primitive emotional traits and an enjoyment in killing their great ancestors because " it ' s fun " . ( TV : " Last of the Time Lords " ) Each Toclafane had built - in life - support and teleportation systems . The shells were capable of flight , and could survive the harsh climate and temperature of space with no side - effects . Concealed within the shell were extendable razor - sharp blades and spikes , used as their up - close - and - personal weaponry . The spheres were also equipped with red laser guns that could disintegrate life forms . ( TV : " The Sound of Drums " ) The spheres could be shot down by an electrical surge of 58 . 5 kiloamperes , with a transferred charge of 510 megajoules precisely . Man - made electrical barriers could be constructed to sustain the right energy level balance needed to successfully fry the technology incorporated into the Toclafane spheres , rendering them useless and making them drop to the ground , although the human head would still survive . ( TV : " Last of the Time Lords " ) History . The last of human ity , scattered across the darkness of space , received a message that said " Come to Utopia " . Because the Utopia Project was set up to find a way to survive the end of the universe , everyone believed they had found a way . Humans attempted to travel to the mythical paradise , ( TV : " Utopia " ) but what they found was a dark , cold and inhospitable world . To survive , the human race " evolved " into the Toclafane , essentially cannibalising themselves and regressing to children . Even so this was not enough , as the universe was still collapsing around them . , using the Doctor ' s TARDIS , travelled to the planet in the year 100 , 000 , 000 , 000 , 000 where he met them . Over time , he became master over them and devised a plan to enable them to change history and survive . He soon saw them as his " children " . ( TV : " Last of the Time Lords " ) As Prime Minister of Great Britain , the Master announced he had made contact with a race of friendly aliens . The Toclafane had tractable , child - like personalities and trusted the Master . The Master had , by this time , converted the TARDIS into a paradox machine , allowing the six billion Toclafane to invade Earth in their own past and change their own history . ( TV : " The Sound of Drums " ) With the Toclafane , the Master built the beginnings of a new Time Lord Empire with the army of six billion Toclafane . ( TV : " Last of the Time Lords " ) The Toclafane invasion was a success . The Master ordered the Toclafane to remove one tenth of the population of Earth . ( TV : " The Sound of Drums " ) They subjugated humanity and forced them to build a fleet of 200 , 000 rockets to take over the rest of the universe . Their plans were thwarted one year after the invasion by the Doctor and his associates . Jack Harkness destroyed the paradox machine with an assault rifle , forcing the Toclafane back to the heat death of the universe . Humanity , aside from those on the " Valiant " , did not remember they had been invaded . ( TV : " Last of the Time Lords " ) A Toclafane later visited Penhaxico Two . ( COMIC : " Escape to Penhaxico " )