Teacher
A teacher was a learned individual employed to teach others, typically in an institution, such as a school.
Two of the First Doctor's first companions were teachers. In November 1963, Ian Chesterton and Barbara Wright, who taught Susan Foreman, followed her to a junkyard as they were worried for her safety. They quickly became caught up in the Doctor's travels. (TV: An Unearthly Child)
The Second Doctor, Jamie McCrimmon, and Zoe Heriot, when visiting Dulkis, met Balan, a teacher and researcher of the residual radioactivity from a blast that happened 172 year prior. (TV: The Dominators)
The Third Doctor befriended Bernard Helmann, a philosophy teacher at Oxford, at the 1960 Campaign for Nuclear Disarmament. (PROSE: Come Friendly Bombs...)
The Seventh Doctor and Ace met Miríl, a teacher on Kirith, and uncovered the truth about the planet's history with him. (PROSE: Timewyrm: Apocalypse)
In 1976, Richard Hawton was taught by a student teacher who he remembered in a response to Doctor Who?'s request for sightings of the then missing Rose Tyler following the Dummy Massacre in 2005, commenting that she looked so much like his student teacher though he reasoned that it surely could not be her. (PROSE: The Doctor Was Involved in the Dummy Massacre)
In 2007, the Tenth Doctor posed as and met many teachers while investigating Deffry Vale High School with Rose, Mickey Smith, and Sarah Jane Smith. (TV: School Reunion)
In 1913, the Tenth Doctor became the human teacher John Smith at the Farringham School for Boys for a short time when travelling with Martha Jones. (TV: Human Nature/Family of Blood)
Clara Oswald, companion of the Eleventh Doctor, became a teacher at Coal Hill School. (TV: The Day of the Doctor) At the school she dated Danny Pink, another teacher. (TV: Into the Dalek, Listen, The Caretaker)
The Voord Nebrin's father was a teacher. (AUDIO: Domain of the Voord)
The Twelfth Doctor became a teacher at St Luke's University. (TV: The Pilot)
According to one account, Rose Tyler became a teacher on Pete's World. (PROSE: The Turning of the Tide)
The Thals believed that Dals had originally been teachers. (TV: The Daleks)
