Mr Smith Mr Smith was a super - computer owned by Sarah Jane Smith who also served as one of her faithful allies . He was located in the attic of Sarah Jane ' s house at 13 Bannerman Road . It was revealed that he was actually a Xylok embedded into the computer . For a brief period of time , he was Sarah Jane ' s enemy , working with a family of Slitheens to destroy Earth . ( TV : " The Lost Boy " ) Biography . Origins . The computer known as Mr Smith housed a sentient and highly intelligent crystal known as a Xylok . In the distant past a Xylok ship had crashed into the Earth , trapping the Xyloks in the crust of the planet . When the volcano Krakatoa erupted , one crystal escaped . Centuries later , Sarah Jane Smith retrieved the living crystal , took it to her home on 13 Bannerman Road , and found it could communicate with her via her laptop . The crystal informed her how to build the computer to house the living crystal . Sarah Jane did not know at this time about the Xyloks or that Mr Smith planned to free the other Xyloks , even at the cost of the planet itself . ( TV : " The Lost Boy " ) Working for Sarah Jane . After she created the computer to house him , Mr Smith helped Sarah Jane , and offered her knowledge on many things . His help at this point however , was mainly confined to hacking other computers and displaying information on alien life forms . He momentarily revealed his dark side to Clyde Langer , presumably because he realised he might get help from the Slitheen . ( TV : " Revenge of the Slitheen " ) Against Sarah Jane . Eventually , Mr Smith was able to team up with members of the Slitheen family on Earth . He helped two of them pose as Luke Smith ' s true parents so that they could kidnap him . Alan Jackson used a computer virus against Mr Smith which disabled him and wiped his database . As a result , Mr Smith forgot his purpose and asked for instructions . Sarah Jane informed him that his mission was to save humanity , which he accepted and fulfilled thereafter . ( TV : " The Lost Boy " ) Reprogramming . After his reprogramming , Mr Smith was of great help to Sarah Jane and Luke during the first part of the Dalek invasion of Earth in the 21st century . He alerted the Smith family to the Earth ' s changed position in space . He detected the presence of incoming space ships , and relayed the message of them to the Smiths . Once the fleet had been identified as Dalek in origin , he amplified an incoming sub - wave message from Harriet Jones . This message allowed a pivotal conference call between Sarah Jane , Martha Jones and Torchwood Three . They formulated a plan of action to contact the missing Tenth Doctor , in the hope that he could help repel the Daleks . In this scheme , Mr Smith vitally linked together all the world ' s phone networks to dial the number of Martha Jones ' phone aboard the TARDIS . Mr Smith ' s efforts were relayed to Torchwood , whose rift manipulator greatly amplified his signal . The power needed to amplify its phone call damaged the computer . Nevertheless , he was able to determine the site of the Doctor ' s TARDIS landing , prompting Sarah Jane to leave Luke in Mr Smith ' s care while she rendezvoused with the Time Lord . ( TV : " The Stolen Earth " ) Later , Mr Smith received the TARDIS base numerals from K9 and linked with the TARDIS and the Cardiff Rift , allowing the Doctor to tow the planet back to its proper place in space and time . ( TV : " Journey ' s End " ) His on screen logo changed to a more fluid graphic and he developed a sense of humour . ( TV : " The Last Sontaran " ) Mr Smith told the team more about the Pied Piper including that he came from the Jeggorabax Cluster , but he needed more information so he asked Sarah Jane to go to the Pharos Institute to collect a part of the meteorite . ( TV : " The Day of the Clown " ) When Martin Trueman was possessing the world to join the Ancient Lights even Mr Smith became controlled and lost connection . ( TV : " Secrets of the Stars " ) He trapped threats with a containment vortex , for example , Mrs Wormwood . ( TV : " Enemy of the Bane " ) Using the sonic lipstick , he teleport ed a Slitheen back to Raxacoricofallapatorius . ( TV : " From Raxacoricofallapatorius With Love " ) Mr Smith received a distress signal and video from a Judoon in a ship crashing to Earth . He told the gang where the ship was . Later on , Sarah Jane , possessed by Androvax , activated Mr Smith ' s self - destruct program , to destroy all of Bannerman Road in sixty seconds . Luke reminded Mr Smith that purpose was the most important thing to a Xylok and his purpose was to protect the Earth ; Mr Smith ' s actions were against his purpose , so he stopped the countdown . ( TV : " Prisoner of the Judoon " ) Feud with K9 . Mr Smith helped Sarah Jane find Rani Chandra , who was in Danemouth , and then put Sarah Jane ' s phone through to K9 to use the black hole to power Eve ' s ship . This allowed K9 to come back . Mr Smith showed disdain for K9 very quickly . ( TV : " The Mad Woman in the Attic " ) Mr Smith and K9 appeared to have had an antagonistic relationship with each other , attempting to one - up each other in the presence of Sarah Jane or the children . ( TV : " The Wedding of Sarah Jane Smith " ) He showed a report on the disappearance of the Mona Lisa and told Sarah Jane that the painting which had Phyllis Trupp in was the actual painting . ( TV : " Mona Lisa ' s Revenge " ) When the Slitheen - Blathereen gave Sarah Jane Rakweed , she had Mr Smith to scan it . He found it harmless , but the morning after , the weed mutated and attacked Luke . When the spores threatened him and Sarah Jane , Mr Smith used his cooling air vents to suck them away . Mr Smith monitored Luke ' s condition during the crisis . When Clyde , Rani and K9 discovered how to stop the Rakweed , K9 sent Mr Smith the frequency level required to sound the alarm bell sound across London ( 1421 . 09 Hertz ) . He did this again when the two Blathereen attacked , causing the Rakweed in their stomachs to be destroyed , creating a build - up of methane gas which caused them to explode all over everyone , including Mr Smith . ( TV : " The Gift " ) When the Nightmare Man put Luke into a deep sleep , Mr Smith used a USB cable to give K9 extra power to contact Luke . He was attacked and damaged by the Nightmare Man , but later recovered . Before K9 left to accompany Luke to university , Mr Smith told him that he could contact him if needed , which K9 took to mean Mr Smith would miss him . ( TV : " The Nightmare Man " ) More adventures . When Androvax returned , Mr Smith trapped him in the containment vortex . ( TV : " The Vault of Secrets " ) When the Automatons removed all the humans from Earth except Clyde and Rani to look for the heir to the throne of their planet , Mr Smith was taken as well , leaving the computer an empty shell . He was returned when the Automatons found the heir . ( TV : " The Empty Planet " ) When Sarah Jane was secretly under attack by Ruby White , she asked Mr Smith to clear her voice from the command alphas . He still warned Clyde that Ruby was dangerous but was shut down by her , having fallen under the control of Mr White . After K9 reset Mr White , Mr Smith was restored and temporarily contained Ruby in a containment vortex before her escape . He later had Sarah Jane ' s voice restored to the command alphas and finally admitted K9 wasn ' t so bad . ( TV : " Goodbye , Sarah Jane Smith " ) He was initially frightened of Sky Smith because of her tendency to blow up electrical devices such as him . ( TV : " Sky " ) As he was not human , he was unaffected by Hetocumtek ' s curse , helping Sky Smith work out what had happened . After he had helped Sky work out how to break the curse on Sarah and Clyde , he teleported the totem pole into the attic , where Clyde destroyed it , lifting the curse . ( TV : " The Curse of Clyde Langer " ) Mr Smith was pleased that K9 did not accompany Luke when he returned from university . He told Sarah Jane the real Joseph Serf had died in a skiing accident in 2007 and analysed a SerfBoard with Clyde and Rani . They found out that it was a simple , low standard laptop . Luke used K9 ' s whistle to speak to Mr Smith in Morse code , alerting Clyde and Rani to get the pen John Harrison was using to torture the Skullion s . Luke and Sky took control of Serf whilst Sarah Jane and Adriana took the Skullions to the roof of the building . Mr Smith had alerted the Skullion species to send a spaceship to Earth to pick up the Skullions . ( TV : " The Man Who Never Was " ) Later life . Sarah Jane and her gang continued to have adventures , defend Earth and save countless lives . Statues would be raised in their honour and they would leave behind a legacy that would last forever . ( PROSE : " The Wedding of Sarah Jane Smith " , TV : " The Man Who Never Was " ) Abilities . Frequently used . He possessed an extensive , but not absolutely complete database of alien life forms and could display them on his screen . ( TV : " Invasion of the Bane " et al ) At the behest of Sarah Jane , this database was later augmented with the Alien Files . ( TV : " Sarah Jane ' s Alien Files " episode 1 ) He secretly monitored the activity and communications of alien ships . ( TV : " Warriors of Kudlak " ) Mr Smith played a fanfare of his own accord when activated ( TV : " Invasion of the Bane " onwards ) as shown when Sarah Jane Smith requested that he stop playing it during his activation following the transportation of Earth to the Medusa Cascade . ( TV : " The Stolen Earth " ) Luke Smith had also requested Mr Smith start in silent mode during Clyde , Rani , K9 and his attempts to spy on Sarah Jane ( TV : " The Wedding of Sarah Jane Smith " ) Mr Smith could relay messages from alien sources and display them on his screen . ( TV : " Invasion of the Bane " , " Warriors of Kudlak " , " Prisoner of the Judoon " , TV : " The Stolen Earth " ) He could scan alien objects in a drawer built into his computer such as telepathic stones . ( TV : " Death of the Doctor " ) Less commonly used . He diverted meteorite K67 from colliding with Earth , using magnetic repulsion . ( TV : " Whatever Happened to Sarah Jane ? " ) He could digitalise a lifeform and store it inside him . ( TV : " The Lost Boy " ) Mr Smith could also readily detect celestial bodies and ships in close proximity to the Earth , such as the other 26 planetary bodies and the Dalek fleet located in the Medusa Cascade . ( TV : " Journey ' s End " ) He could tap into every phone network on Earth . ( TV : " The Stolen Earth " ) The computer seemed to have heavy armaments , including projectile weapons . ( TV : " The Lost Boy " ) Mr Smith was also capable of entrapping alien threats within a containment vortex and sapping their weapons of their energy . ( TV : " Enemy of the Bane " , " The Vault of Secrets " , " Goodbye , Sarah Jane Smith " ) Mr Smith had a tracking device with an aerial satellite scan . Luke , Rani and Clyde used it to track down Sarah Jane when she was meeting Peter Dalton . ( TV : " The Wedding of Sarah Jane Smith " ) Mr Smith also had a self destruct setting which was capable of destroying the whole of Bannerman Road . This was activated by the Veil Androvax when he possessed Sarah Jane ' s body . When Clyde , Rani , Luke and Captain Tybo found traces of Androvax in Sarah Jane ' s House , Mr Smith warned them to leave as soon as possible as the house would blow up in 60 seconds . ( TV : " Prisoner of the Judoon " ) He could be used to contact K9 inside the black hole . ( TV : " The Mad Woman in the Attic " ) He had an air ventilation system with large fans hidden under his computer screen . ( TV : " The Gift " ) He could give K9 extra power via USB cable . ( TV : " The Nightmare Man " ) He could disable Mars Rovers and possibly other craft . ( TV : " The Vault of Secrets " ) He had a " medi - scan " that could perform a full medical analysis of a subject . ( TV : " The Gift " , " The Vault of Secrets " , " Goodbye , Sarah Jane Smith " , " Sky " ) He had a " voice remover " that could remove voices from the system so that certain people could not access him . ( TV : " Goodbye , Sarah Jane Smith " ) He could tap into the teleport s of alien ships that are on or close to Earth and use them for Sarah Jane ' s purposes . ( TV : " The Gift " , " The Curse of Clyde Langer " ) He could use an energy reversal beam to reverse an enemy ' s actions back upon them and their teleports . ( TV : " From Rax . With Love " ) He could communicate with other planets for various purposes including calling for teleports and rescue . ( TV : " The Wedding of Sarah Jane Smith " , " The Man Who Never Was " ) He could pick up transmissions on all frequencies including K9 ' s command frequency over great distance even when coming from just a dog whistle . ( TV : " The Man Who Never Was " ) He could make replicas and duplicates of things such as the a replica black diamond of Earnfield . The museum staff did not realise the difference between the replica and the original . ( AUDIO : " The Time Capsule " ) Personality . Initially , Mr Smith comported himself with a cold , clinical mindset , more like an actual computer than a living being . When his true intentions were revealed , he acted maliciously and cruelly , becoming extremely ruthless and megalomaniacal , yet justified his actions by stating they were part of his " purpose " . As such , Mr Smith was sociopathically logical and had no complaints about mass - murder or causing people who were thought to be his friends immense pain and suffering . He was even capable of a sadistic laugh , in spite of the fact that he was meant to be a computer , showing that he was actually a living being in crystalline , later electric , form . ( TV : " The Lost Boy " ) After his memory had been wiped by the Armageddon Virus , ( TV : " The Lost Boy " ) Mr Smith ' s personality changed greatly . He became much friendlier and more amiable . He would make jokes . He bade Maria a fond farewell when she left for America . ( TV : " The Last Sontaran " ) He showed great compassion for Sarah Jane ' s younger friends , especially her son Luke . He vowed to protect him from the Dalek s ( TV : " The Stolen Earth " ) and did everything he could to save him from the Rakweed . ( TV : " The Gift " ) , He also showed great concern for Sarah Jane after her heart was broken by Peter Dalton and the Trickster . ( TV : " The Wedding of Sarah Jane Smith " ) It is heavily implied that an unresolved romantic tension exists between Mr Smith and Sarah Jane throughout the series , which is simply unaided by a drastic contrast in species . When K9 returned to Bannerman Road , Mr Smith entered into a deep rivalry with him , the two constantly trying to one - up each other in the technical support , and referring to each other as " the dog " and " that computer " . ( TV : " The Wedding of Sarah Jane Smith " et al ) However , when it appeared K9 was broken , Mr Smith refrained from calling him a dog and even expressed concern . Before K9 left with Luke for Oxford University , Mr Smith told K9 that he could call him if needed , which K9 took to mean he would miss him . Mr Smith didn ' t deny it , just telling K9 goodbye . ( TV : " The Nightmare Man " ) However when around others he still maintained his animosity for " the dog " though after K9 saved him from Mr White he finally called K9 by name and admitted he wasn ' t so bad , saying he ' d met worse . K9 returned the sentiment . ( TV : " Sarah Jane ' s Alien Files " episode 3 , " Sarah Jane ' s Alien Files " episode 4 ) . ( TV : " Goodbye , Sarah Jane Smith " ) Despite this , he was still pleased when K9 didn ' t return with Luke from Oxford , showing there was still a rivalry between the two supercomputers . ( TV : " The Man Who Never Was " ) He originally feared Sky due to her shorting out the power , but he got over it . ( TV : " Sky " ) Despite his intelligence , Mr Smith could be literal - minded , such as when he gave Sky Smith information about the general details of school life while skipping over relatively minor information , so she thought that " toad - in - the - hole " actually had toad in it . ( TV : " The Curse of Clyde Langer " )