Mr

Mr — or Mister — was an honourific applied to men, on Earth and elsewhere, or rather, as explained, those who did not hold a rank such as Captain or General. (AUDIO: The Devil You Know) "Mister" could also serve as a form of address on its own, usually when addressing a stranger. (TV: The Talons of Weng-Chiang, Father's Day, The Lazarus Experiment, The Eleventh Hour) or to prompt them for a name. (TV: Frontios, AUDIO: Backtrack)

It was an equivalent to Miss or Mrs for women, (AUDIO: Whodunnit?, TV: Fury from the Deep, The Evil of the Daleks) and to Trau in some 51st century cultures for men. (TV: The Caves of Androzani)

On some occasions, the Doctor would clarify that he was not a "Mister" but a "Doctor". (TV: Colony in Space, AUDIO: Death Match, TV: Father's Day)

After retiring from UNIT, Mike Yates chose to become a "Mister" again, leaving "Captain" behind. (AUDIO: The Stuff of Nightmares, Call to Arms)