Lying
A lie or lying was the action of telling something that was not the truth. A person who told lies was a liar.
The Doctor
Among their companionss, the Doctor was know for their propensity to lie.
The First Doctor lied to Ian Chesterton, Barbara Wright and Susan Foreman about the fluid link requiring mercury in a bid to investigate the Dalek City. After they initially escaped the city without the fluid link, the Doctor discovered that, ironically, he really did need more mercury. (TV: The Daleks) When he met his twelfth self, the Doctor lied that his refusal to regenerate was out of his right to live and die as he was. He later confessed that, in truth, he simply feared becoming someone else. (TV: Twice Upon a Time [+]Loading...["Twice Upon a Time (TV story)"], PROSE: Twice Upon a Time [+]Loading...["Twice Upon a Time (novelisation)"])
The Third Doctor told Sarah Jane Smith that he rarely lied. (TV: The Time Warrior)
While in London, the Ninth Doctor lied to Rose Tyler that he was leaving her flat to get some privacy and was not going to wander off only to then investigate the Slitheen crash. (TV: Aliens of London) He also lied to Jack Harkness that his sonic screwdriver could not open a door in order to trick Jack into revealing he possessed a Sonic blaster. (TV: The Doctor Dances) One Dalek accused the Doctor of lying when he declared he personally killed the Dalek race during the Last Great Time War. (TV: Dalek) The Doctor himself accused the Editor on Satellite Five of lying to the people within the Fourth Great and Bountiful Human Empire. (TV: The Long Game)
The Tenth Doctor occasionally lied. (TV: School Reunion, The Fires of Pompeii) He believed he did it to make himself feel better. (TV: Gridlock) Although, he occasionally lied for strategic purposes, such as tricking the Family of Blood that he was still in human in order to tamper with their ship's equipment. (TV: The Family of Blood) He could also deduce when others were lying, such as Novice Hame's lie that the Sisters of Plenitude were not harming patients on New Earth (TV: New Earth) and that Sarah Jane Smith was actually researching Krillitane activity rather than writing a journal article about the local high school's improving exam results as she claimed. The Doctor himself likewise initially lied to her that he was a human Physics teacher at the school called John Smith. (TV: School Reunion) He also claimed "John Smith" was his real name to a group of tourists when it actually wasn't, a lie the group saw through. (TV: Midnight)
The Eleventh Doctor made a habit of lying, both to companions (TV: Flesh and Stone, The Lodger, The Impossible Astronaut, The Almost People, Let's Kill Hitler, The Wedding of River Song, The Name of the Doctor) and enemies, (TV: Victory of the Daleks, The Doctor's Wife, The Snowmen, Journey to the Centre of the TARDIS, Nightmare in Silver) so much so that Amy Pond could sometimes tell when he was lying. (TV: The Doctor's Wife, Asylum of the Daleks) This led River Song to declare "Rule One: The Doctor lies." (TV: The Big Bang, The Wedding of River Song) The Eleventh Doctor even lied about his age, so much so that was unsure he was even lying about it when speaking to the War Doctor. (TV: The Day of the Doctor) Given his history, the Time Lords constructed a Truth Field on Trenzalore to force the Doctor to speak truthfully. (TV: The Time of the Doctor)
The Twelfth Doctor also lied. He lied to Clara Oswald, putting her in a dream scenario to test how far she would go to convince him to save Danny Pink, (TV: Dark Water) and about finding Gallifrey (TV: Death in Heaven and Last Christmas) He later lied to Bill Potts that was assisting the monks in order to test if she was under their control. (TV: The Lie of the Land) Ohila confessed to the Doctor that she always assumed he was lying because "it save[d] time." (WC: Prologue) Clara noted however that the Doctor lied with purpose, trying to give those in danger hope so they would run from danger faster. (TV: Flatline) When the Twelfth Doctor returned to Gallifrey, he claimed to have information about the Hybrid. (TV: Hell Bent) A Time Lord author later believed that this had been a lie, suspecting that the Doctor was simply using the Time Lords' fear of the Hybrid against them as part of his plan to rescue Clara Oswald. (PROSE: A Brief History of Time Lords)
Yasmin Khan felt the Thirteenth Doctor hadn't been entirely honest with her whilst investigating her missing memories associated with the Division. (TV: The Halloween Apocalypse)
Others
A Time Lord author considered that the lies of Rassilon and his elites were the only constant in the history of Gallifrey. (PROSE: A Brief History of Time Lords) According to the Spy Master, the Time Lords lied about the Doctor's origins, and that they were actually the Timeless Child. (TV: The Timeless Children)
The Brigadier lied to the Third Doctor about doing no harm to the Silurians on Wenley Moor, only to blow them up. (PROSE: Doctor Who and the Cave Monsters)
Davros was known to tell lies. (TV: Genesis of the Daleks; AUDIO: Purity, Guilt, The Juggernauts, etc.) This deceptive streak was passed on to the Daleks. (TV: The Daleks, The Evil of the Daleks, Victory of the Daleks) et. al) When he met the Dalek Prime Strategist, the Tenth Doctor came to believe that its claim of being proud of using a ruined Dalek War Machine was a lie, sympathising with lying as a coping mechanism. (COMIC: Defender of the Daleks)
A voice analyser could detect when one was lying. (TV: The Bounty Hunter)
Sister Spurrina declared the High Priestess lied to her about Pompeii's survival through the Pyrovile. (TV: The Fires of Pompeii)
The Cybermen lied to Miss Hartigan in order to trick her into becoming the Cyber-King. (TV: The Next Doctor)
In her time with the Doctor, Clara Oswald became adept at lying something that, along with her lack of scruples in doing it, gave the Doctor concern. (TV: Flatline) She later boasted of being "an incredible liar", something that Danny Pink mournfully agreed with. (TV: Death in Heaven)
After the the defeat of the Slitheen family on 7 March 2006, Mickey Smith (TV: World War Three [+]Loading...["World War Three (TV story)"]) wrote on his website that he did not "fake evidence, or make exaggerated claims", when refuting the possibility he was a liar, having read many lies on the Internet. (PROSE: Hoax This! [+]Loading...["Hoax This! (short story)"])