An unnamed Time Lord who, although not evil per se, took delight in mischievously meddling. The Doctor encountered him on Earth in 1066, where the Monk - clearly one of the Doctor's contemporaries - was hiding in a monastery, planning to give powerful weapons to King Harold.

This would enable the English sovereign to win the Battle of Hastings and defeat William the Conqueror, changing the course of history. The Doctor removed the dimensional stabiliser from the Monk's TARDIS, frustrating his efforts to escape Earth.

However, he clearly managed to, as the two foes next crossed swords on the planet Tigus, and again later back on Earth, in Ancient Egypt, where the Monk was assisting the Daleks to build a Time Destructor.

The Doctor altered the Monk's TARDIS to resemble his own's external appearance, thus confusing the Daleks. He also removed the ship's directional unit, catapulting the Monk and his TARDIS to a distant ice planet, with little hope of an early escape.

Since 1966 the Monk never reappeared on TV however the character made an appearance in the New Adventure - No Future.