Land of Fiction

The Land of Fiction is a pocket universe inhabited by characters from various works of fiction, hence the name.

The Land of Fiction in the Television Series
Following their adventure with the Dominators and Quarks on Dulkis, the Doctor, Jamie, and Zoe found themselves trapped in this universe, encountering such varied characters as Lemuel Gulliver, Rapunzel, D'Artagnan, and Medusa. They found this realm to be under the control of a malevolent being known as the Master of the Land.

In time, the Doctor learned that the Master was in fact a benign old man, a writer of boys' fiction from Earth in the year 1926 who had also been trapped in this universe and taken over by a computer, the Master Brain, the Land's real ruler. Zoe and Jamie were able to overload the Master Brain's systems, destroying it and freeing the old man from its control. Once the Master Brain was destroyed, the old man was returned to Earth, while the Doctor and his companions were returned to the TARDIS ("The Mind Robber").

The Land of Fiction in the Expanded Universe
The Virgin New Adventure novel "Conundrum" revealed that the Land of Fiction had been created to entertain the Gods of Ragnarok. As part of his elaborate scheme to gain revenge on the Doctor, the Monk reactivated the Land and installed a mentally unstable boy from 1993 Earth, named Jason, as its new Master. Jason constructed a town called Arandale, inhabited by various fictional characters such as the White Knight and Dr. Nemesis. He then trapped the Seventh Doctor, Ace, and Benny in this scenario. By tricking Jason into introducing highly disruptive McAllerson's Radiation into the Land, the Doctor was able to escape, and at his request the Time Lords placed beacons around the Land to warn away other travellers in space and time who might become trapped there.

The actions of Kadiatu Lethbridge-Stewart during the events related in "Set Piece" created a space-time anomaly which allowed energy from the Land of Fiction to bleed into the real universe. This created the Miracle, an energy source which for a time sustained the dying planet Detrios. It also re-activated Jason, who sought to gain revenge on the Doctor by creating a fictional version of the Doctor, Dr. Who. Jason then employed Dr. Who in a plot to assassinate Queen Elizabeth II. Although the Queen was killed by Dr. Who, Jason's distaste for bloodshed moved him to use his powers to restore her to life. Jason then assisted the real Doctor in sealing off the anomaly, after which the Doctor wiped Jason's memory and returned him to Earth ("Head Games").