The Monk

Mortimus (also known as the Monk, the Meddling Monk or the Time Meddler) was a former friend of the young Doctor and later his enemy.

Youth
At the Academy, Mortimus was a friend of the Doctor's, and a member of a cabal of ten rebellious young Gallifreyans at the Academy known as "the Deca". (PDA: Divided Loyalties)

Reunion with the Doctor
Mortimus was the owner of a Mark IV TARDIS and said that he had left the Doctor's home planet some fifty years after the Doctor.

He decided that he liked to meddle with history, specifically the history of Earth, and to change it for his own amusement and for what he considered to be the better &mdash; lending mechanical assistance to the builders of Stonehenge; giving Leonardo da Vinci tips on aircraft design; and, when, the Doctor's first incarnation, encountered him, he attempted to prevent the Norman Conquest of 1066 as part of a plan to guide England into an age of technological prosperity. On that occasion he wore the guise of a monk in order to gain the trust of the locals, hence the name by which he is most often referred.

The Monk was at this time a well-meaning but childish man who was not half as clever as he thought he was, and who never seemed to realise the seriousness of what he was doing.

The Doctor sabotaged Mortimus' TARDIS, making it the same size inside as outside.(DW: The Time Meddler)

Ally of the Daleks
The Doctor encountered him again on the planet Tigus, where Mortimus attempted to sabotage the lock on The Doctor's TARDIS. (DW: The Daleks' Master Plan)

They met again in ancient Egypt where they also encountered the Daleks who had followed the Doctor there. Mortimus decided to ally himself with the Daleks, in order to avoid being exterminated himself. While there, the Doctor tinkered with the chameleon circuit from Mortimus' TARDIS, making it assume various shapes, finally that of a police box and also stole its directional unit, leaving Mortimus stranded in a cold, icy location. (DW: The Daleks' Master Plan)

Ally of the Ice Warriors
Mortimus then teamed up with the Ice Warriors and battled the Doctor in a complex scheme involving alternative Earths and a plan to build a giant sonic weapon. Mortimus now preferred his own TARDIS to appear as a police box, did not wear a monk's habit, and referred to himself as the Time Meddler. (DWM: 4-Dimensional Vistas)


 * Sometime after, he regenerated at least once.

On the run from the Sleeze Brothers
At some point in the 21st century, the Monk tried to rig elections in what might have been the United States to stop President Sintatra from winning a third term of office. As he began this mission, he landed his TARDIS on a busy freeway. The Sleeze Brothers, El Ape and Deadbeat, collided into it, causing significant damage to their vehicle. At the same time, the companion-less Doctor landed his TARDIS in the same area.

Besieged by both angry brothers and an irate Doctor, the Monk slipped back into his TARDIS and took off. The Brothers then hijacked the Doctor's TARDIS at gunpoint and ordered him to follow the Monk's TARDIS through time. A chase ensued, and the two TARDISes flitted through time to several famous mysteries in Earth's history. Eventually, the Doctor and the Sleeze Brothers caused the Monk's TARDIS to implode, which apparently caused the creation of the Bermuda Triangle. How, when, or if the Monk reconstituted his TARDIS wasn't clear. (DWM: "Follow that TARDIS!)"

Death's Champion
Mortimus then created a series of alternative timelines (NA: Blood Heat, The Dimension Riders, The Left-Handed Hummingbird, Conundrum) in a scheme employing the Chronovore Artemis. Mortimus now used his real name and posed as a 1976 record executive in England. He had also, at this time, served as Death's Champion in the same way that the Doctor served as Time's Champion. In so doing, he had made himself servant to a being much more powerful and intelligent than himself. (NA: No Future)

Behind the Scenes
There was for some time speculation that the Monk was actually an earlier regeneration of The Master or the War Chief; the former is stated as fact in The Doctor Who Role Playing Game, a likely apocryphal source. However, this theory has been contradicted by the novelized depictions (noted above) of the Doctor's other encounters with the Monk. The Monk has the distinction of being the first Gallifreyan other than the Doctor and Susan to be seen in the series.