Marnal was the Castellan on Gallifrey before the Doctor left the planet. Marnal was sent by the Time Lords to the Shoal to investigate the threat of the Vore to Gallifrey. He destroyed the Shoal after a meeting with Larna, a Time Lady from Gallifrey's future.
Marnal threatened to expose fellow Time Lord Ulysses' secret of having a hybrid son. Ulysses wiped Marnal's memory with his TARDIS' telepathic circuits and dumped him on Earth in England, 1883. He was placed in the care of a Mrs Gate. Under the name Marnal Gate, Marnal became a science fiction author, and met Mervyn Peake, who illustrated one of his novels, and H.G. Wells. Marnal had amnesia about Gallifrey and the Time Lords, but he remembered enough to write novels containing the entire history of Gallifrey; he did not know Gallifrey was a real place.
Marnal had a son on Gallifrey, who visited him during the 1970s and told him that the Doctor was the renegade Time Lord who stole his TARDIS. He also had four adopted daughters on Earth from his wives' previous marriages, whom he described as parasites.
In 2005, he regenerated from his twelfth to his thirteenth and final incarnation. The surge of artron energy restoring his synapses in the regeneration returned his memory. He recruited his hospice nurse, Rachel Rowley, and used a bottle universe to learn about the destruction of Gallifrey and the history of the Eighth Doctor.
Enraged at the Doctor's actions, as well as the "theft" of his old TARDIS, he intended to make the Doctor pay for his crimes. However, the pair created an uneasy alliance when the Vore began to invade Earth. Marnal became convinced that he and the Doctor should restore Gallifrey, but he was killed by the Vore before any plan could be finalized. Before he died, the Doctor told him that he was his childhood hero, which seemed to surprise Marnal before passing. (PROSE: The Gallifrey Chronicles)
In an alternate timeline, Marnal was remembered as the man who went on impossible crusades and who fought battles without knowing his enemy. The latter was to become known as "Marnal's error". (PROSE: The Infinity Doctors)
Marnal's novels included:
- The Kraglon Inheritance
- The Witch Lords
- The Emergents
- The Giants
- The Hand of Time (published in 1976)
- The Time of Neman
- The Beautiful People
- Marnal's Journeys or the Modern Crusoe
- Day of Wrath
- The Monkey to Time Saga (published in November 2001)
- Valley of the Lost
Behind the scenes
- Many of Marnal's works are references to the working titles of previous televised Doctor Who stories. They include The Witch Lords (TV: State of Decay), The Giants (TV: The Giants), The Hand of Time (TV: The Hand of Fear), The Kraglon Inheritance (TV: The Two Doctors), Day of Wrath (TV: Four to Doomsday), The Time of Neman (TV: Arc of Infinity) and The Monkey to Time Saga (possibly The Key to Time season ).
- Marnal's son is heavily implied to be the Master. In author Lance Parkin's AHistory, he says the visit of Marnal's son in the 1970s (during which the unnamed son was "on the run") is set during UNIT's hunt for the Master in the television story Colony in Space.