Prisoner Zero Prisoner Zero was a multi - form shape - shifting alien , held prisoner by the Atraxi for certain crimes . He escaped to Earth when the TARDIS explosion caused cracks throughout time and space , hiding in an extra room of Amelia Pond ' s home for twelve years until he was tricked into revealing himself by the freshly regenerated Eleventh Doctor and recaptured by his jailers to be executed . Before being taken away , he warned the Doctor against the Silence . Biography . In 1996 , Prisoner Zero was a captive in an Atraxi extra - dimension al prison . When a crack in the universe opened into Amelia Pond ' s bedroom wall , Prisoner Zero escaped through to Amelia ' s house in Leadworth . It hid in a room in Amelia ' s house , placing a perception filter on the room ' s door so it would not be found . It hid on Earth for twelve years , watching Amelia grow up . It sometimes ventured into the village , posing as comatose people in Royal Leadworth Hospital whom it had established a psychic link with , a process that took months . If the person it was copying was dreaming about having someone else with them , Prisoner Zero would appear to be multiple lifeforms touching each other . It was actually one creature with many limbs and orifices . The forms it took were of comatose people . In 2008 , Rory Williams , who worked at the hospital as a nurse , took pictures of them with his mobile phone , knowing the people he saw shouldn ' t be up and about . It was during this time that Prisoner Zero established a psychic link with Amelia ( later Amy ) Pond . The Eleventh Doctor belatedly returned to Amelia ' s house to save her from the multi - form . After Amy had seen its natural form , Prisoner Zero took a shape - shifted form but was confused as to which voice to use for each form . The Atraxi , who had followed the Doctor , broadcast a global warning that they would incinerate " the human residence " , Earth , if Prisoner Zero did not surrender . After escaping from Prisoner Zero , the Doctor and Amy went into the village square , where residents of Leadworth were taking pictures of the Sun , obscured because the Atraxi had put a force field around the Earth . The Doctor noticed that Rory was facing the other way , taking a picture of Prisoner Zero , who was disguised as a man with a dog . The Doctor attempted to draw the Atraxi to Prisoner Zero by overloading all the electrical devices in the surrounding area with his extraterrestrial sonic screwdriver , but the screwdriver burnt out and Prisoner Zero escaped again . Prisoner Zero went to the hospital and killed all the doctors and nurses . It took the form of a woman with two children to fool Amy and Rory , but gave itself away by talking with the woman ' s voice through a child ' s mouth . It snarled at Amy and Rory and chased them down the corridors . The Doctor arrived through the window just in time , and revealed his master plan to Prisoner Zero . Believing that surrender would mean execution , Prisoner Zero said it was prepared to die in flames with the whole planet . The Doctor suggested Prisoner Zero open another crack to escape , but Zero said the cracks were not its doing , but cracks in the skin of the universe . It taunted the Doctor about his lack of knowledge . " The Doctor in the TARDIS doesn ' t know . " It added that " the Pandorica will open . Silence will fall " . When cornered by the Doctor , who had given the Atraxi Prisoner Zero ' s location and pictures of all its previous disguises , it tried to avoid Atraxi detection by using a psychic connection with Amy to imitate her younger self and the Doctor . The Doctor thwarted this by stimulating Amy ' s recent memory of Prisoner Zero and forcing it to take on its own form . The Atraxi detected and secured Prisoner Zero , as it gave its final warning : " Silence , Doctor . Silence will fall " . ( TV : " The Eleventh Hour " )