Lying

A lie or lying was the action of telling something that was not the truth.

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)

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)

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) 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)

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) 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)

The Doctor would also lie about his name. In order to prevent him lying, the Time Lords constructed a Truth Field on Trenzalore to force him to speak truthfully. (TV: The Time of the Doctor)

According to, the Time Lords lied about the Doctor's origins, and that they were actually the Timeless Child. (TV: The Timeless Children)

A voice analyser could detect when one was lying. (TV: The Bounty Hunter)