The Beast ( The Impossible Planet ) The Beast was a Demon imprisoned in the centre of Krop Tor . He claimed to have existed before the creation of the Doctor ' s universe . He identified himself as Satan , among many religious representations of him . Biology . The Beast ' s physical body resembled a massive humanoid with crimson skin , two large , ram - like horns ( one of which was broken half way ) projecting from its head and a corpse - like face . ( TV : " The Satan Pit " ) The Beast could manifest himself through electronic media , including computer voices and hologram viewers . Its mind could leave its body and possess a single hive mind of the Ood collectively and / or a single human individually . It had the power of telepathy and , through a host , telekinesis . Possession of a human subject affected the host ' s skin , causing strange markings to appear all over their face and body ; and vocal cords , allowing them to speak at different pitches simultaneously . Whether a single human or a hive mind , the eyes of those possessed by the beast glowed a fiery red . The Beast could also project fire from his mouth , as could its possessed hosts . Its hosts could also physically survive in a vacuum indefinitely . ( TV : " The Impossible Planet " ) Biography . Origins . The Beast claimed to have existed before the universe , a claim the Tenth Doctor found troubling to accept or consider as he believed nothing could have existed before the universe . The Beast had been at battle with the Disciples of the Light . The Disciples , who themselves existed before the universe , bound it in giant chains and confined it to a pit in the centre of Krop Tor , a planet in orbit around the black hole K37 Gem 5 . If it ever tried to escape , the field holding Krop Tor in orbit would collapse and the planet would be sucked into the black hole , taking the Beast with it . Despite this , the Beast claimed that it was the basis of the Devil - figure in all religions . The Doctor believed this to be because the Beast ' s existence seeped into the subconscious of all sentient beings . Deities the Beast inspired included the Kaled God of War and the " horned beast " for Draconia , Vel Consadine and Dæmos . ( TV : " The Satan Pit " ) Encounter with the Walker Expedition . In the year 43K2 . 1 , the Walker Expedition came to Krop Tor , searching for the source of energy that kept the planet from falling into the black hole . The Beast possessed Toby Zed via the text transcribed into a notebook . The Beast used Toby ' s body to go outside , but he was heard by Scooti Manista , the base ' s maintenance officer , when she went to deliver Toby ' s expenditure . While investigating , Scooti discovered the possessed Toby standing on the surface . At first it tried to draw Scooti towards it by hypnotising her , but she managed to break free . Angered , the Beast , through Toby , began to use its telekinetic abilities to break the glass in the section Scooti was in . Scooti tried to escape , but the doors had been sealed , trapping her . Soon the glass was shattered and she was pulled out into the vacuum . After Ida Scott and the Tenth Doctor went down to investigate the bottom of the mine shaft , the Base ' s Ood were taken over , causing them to attack the other members of the Expedition . ( TV : " The Impossible Planet " ) Upon the Ood ' s defeat , the Beast planned to escape by keeping its spirit in Toby ' s body , leaving its physical body behind . The Tenth Doctor managed to destroy the force holding Krop Tor in orbit . The Beast ' s spirit was destroyed when Rose Tyler caused Toby ' s body to be pulled into the black hole , followed shortly by the Beast ' s original body , which was destroyed along with Krop Tor . However , it claimed that it would never be truly destroyed . ( TV : " The Satan Pit " ) Return of the Beast . Far from being killed after passing through the event horizon of the black hole , the Beast found itself reconstituted and revived on the other side of the cosmos . It went to Earth where it assumed the form of Martha Jones and used the TARDIS ' telepathic circuits to contact the Doctor . As Martha , it asked the Doctor if she could rejoin him in his adventures , but he refused . They were then chased to the TARDIS by the Cybermen , which were actually a psychic projection created by the Beast . There , the Beast revealed itself and told the Doctor that he would use his TARDIS to conquer time and space . The Doctor then asked the Beast to turn into Martha again , so it was small enough to push into the time vortex . The Doctor revealed that he knew all the time it wasn ' t her , because she would phone him as she didn ' t know how to use the TARDIS ' telepathic circuits . ( COMIC : " The Beast Is Back in Town " ) Personality . The Beast had a narcissistic personality , constantly exalting itself and its achievements and referring to itself by various grandiose epithets . It was also exceedingly arrogant , dismissing all other creatures as its inferiors and believing itself invincible . In addition to being an arrogant narcissist , the Beast was also a ferocious killer . The Beast had an extremely manipulative and cunning nature , and was proud of the acts it set into motion , laughing when the Tenth Doctor deduce d its plans to escape Krop Tor . The Beast would even sadistically prey on people ' s fears and guilty feelings to shake them and leave them feeling vulnerable . Able to see into the future , the Beast used this precognitive insight against others , foretelling twisted interpretations of what would befall them , with enough honesty preserved in his statements to keep them plagued with dread . ( TV : " The Satan Pit " ) Other references . Abaddon was the " son of the Beast " . ( TV : " End of Days " ) When Drew Blayney , leader of the Brimstone Skulls motorcycle club , was possessed by one of the ritual motorcycle s , he drew upon the image of the Beast as one of his childhood fears . ( COMIC : " Jetsam " ) Mr Smith once noted that the Beast was on the Judoon ' s most - wanted list , but was not as high on it as Androvax . ( TV : SJAF 6 ) On Trenzalore , the Great Intelligence mentioned to Madame Vastra that the Doctor himself had been living in " darker and darker shades " , and that he would eventually be known as the Beast and the Valeyard . ( TV : " The Name of the Doctor " ) When Sarah Jane Smith and Maria Jackson asked Mr Smith to identify the species of Uvlavad Kudlak Mr Smith briefly showed them an image of the Beast . ( TV : " Warriors of Kudlak " )