The Monk (The Book of Kells)

One incarnation of the Renegade Time Lord often dubbed the Monk fashioned himself as a hero constantly at odds with both the Doctor and the Laws of Time, taking upon human companions of his own in his quest to alter history for the better. After the loss of his companion Tamsin Drew at the hands of the Daleks, the Monk chose to blame the Doctor, and became fixated on getting revenge on him.

Travels with Lucie Miller
Some time after regenerating, the Monk placed a wanted ad for a willing fellow traveller and chose Lucie Miller as his new companion. Together they met Caligula and the Sensorites, and watched a final of Thordon's Got Talent, before crash-landing in medieval Ireland due to the Monk's malfunctioning "directional whatsit". The pair sought shelter in the Abbey of Kells until the Monk could finish repairs. (AUDIO: The Resurrection of Mars)

In Ireland in 1006, the Monk sought an artefact known as the Book of Kells, intending to take it away from its predicted destruction, but also hoping to use the artistic skill of its creators to create a new printed circuit to replace a damaged component in his TARDIS. During this time, he once again encountered the Eighth Doctor after grounding his TARDIS with a Time Scoop. (AUDIO: The Book of Kells)

After escaping Kells, Lucie and the Monk went to the planet Questus, where the Monk had travelled back in time to kill the parents of a dictator in an avalanche to prevent the dictator's birth. At this point, after being dragged out of the avalanche, Lucie tired of the Monk's meddling and began to consider his actions amoral, to the point of calling him a murderer. After this, the Monk "dumped" her on Deimos Moonbase in the 23rd century, deliberately placing her there in an attempt to grab the Doctor's attention.

Reawakening the Ice Warriors centuries before they were meant to in order to give them the opportunity to terraform Mars back to how it was prior to their hibernation, the Monk planned to allow them to kill thousands of human colonists in the 23rd century, rather than billions on Halcyon a thousand years later. The Monk used Lucie to stop the Doctor from exploding a bomb that would have defeated the Ice Warriors. Realising he had been unsuccessful in distracting the Doctor, the Monk created an artificial gravity eddy to forcibly bring the Doctor back to Deimos. The Monk took the Doctor's companion, Tamsin Drew, to the aftermath of the Ice Warriors' attack on Halcyon around the 33rd century, convincing her that the Doctor was responsible for the billions of deaths there, and subsequently showing her him apparently collaborating with the Ice Warriors in killing 600 people on a passenger rocket.

Following the conclusion of the crisis, Tamsin told the Doctor that she had "had enough" of what she considered only looking out for his friends and the Web of Time, and was unable to forgive him for condemning the people of Halcyon to their fate, choosing to leave with the Monk. The duo set off to find "some old friends who also [had] a score to settle with the Doctor" to "combine their talents". (AUDIO: The Resurrection of Mars)

Helping the Daleks
The Monk helped the Daleks invade Earth as they had in the 22nd century. In exchange for reviving the Dalek Time Controller - when the Daleks realised they needed someone with superior temporal engineering knowledge to their own to repair it - the Daleks promised him anything he desired. He used a Dalek virus from the far future and infected the Earth. He ejected the virus into Earth's atmosphere and moved forwards in time three years, and gave Tamsin the job of stealing human artefacts from museums for his personal collection. He lied to Tamsin, telling her that he was saving the artefacts for when the human race got back on its feet, but he knew the whole time the Daleks would wipe all humans out as part of the Dalek Time Controller's plan to turn the Earth into a plague planet which would be used to infect all of the planets whose inhabitants would threaten the Daleks in the future. (AUDIO: Lucie Miller)

After the Daleks destroyed the collection in an attempt to kill the Doctor, and then coldly exterminated Tamsin, the Monk was devastated that he had allowed someone he had feelings for to die. Wishing not to cause any more death, he decided to help the Doctor. He saved Susan Campbell and him from the bomb that destroyed the Daleks. Under duress from the Doctor, who finally deduced who had helped the Dalek Time Controller, the Monk revealed it had been he who had released the plague on Earth. He was then ordered to leave the Doctor's sight after the Doctor found out that he had deployed the virus on Earth. He also revealed he had picked up the Doctor's TARDIS approaching the 22nd century, and prevented his arrival in time to stop the invasion from truly getting underway. (AUDIO: To the Death)

Revenge on the Doctor
The Monk was deeply affected by the death of Tamsin Drew. In his despair, he formulated a plan to remove the Doctor from history so that Tamsin's death would never come to pass, convincing himself that the Doctor alone was responsible. He located Sophia, a time-sensitive Human/Hetrodon hybrid in ancient Greece and used her abilities to create a hole in space-time, which the Monk planned to use to take the Doctor's place in history. (AUDIO: The Secret History)

His early experiments resulted in the Seventh Doctor taking the place of the Third Doctor on Delphin Isle, (AUDIO: The Defectors) and the Sixth Doctor taking the place of the Second Doctor in a Cyber-Tomb in the Kuiper Belt. (AUDIO: Last of the Cybermen) However, with the aid of their companions, the displaced Doctors were able to realise how their past selves would have dealt with the crisis and act accordingly before the Monk's influence was undone and the original Doctors returned. (AUDIO: The Defectors, Last of the Cybermen)

Finally, the Monk lured the Fifth Doctor to Constantinople in the year 540 in the place of the First Doctor, where he successfully replaced the Doctor's timeline with his own after putting the Doctor in a position where he would have to let alien healers take action on Earth or preserve history and let innocent people die. However, Sophia was able to sense the distortion to history as the Monk's casual interference made things worse, and used her abilities to bring the Doctor back into existence. The Doctor brought a group of Antoim warriors to Earth in order to blackmail the Monk into restoring the Doctor's timeline, the Monk faced with being killed by the Antoene for the Doctor's actions and the Doctor only willing to share his plan to stop them if the Monk restored his timeline. Lost for any better options, the Monk obliged before fleeing once again, informing the Doctor that he would return again, although the Doctor dismissed that plan as unimportant. (AUDIO: The Secret History)

Personality
Lucie Miller called the "Abbot Thelonius" Monk a "murdering lunatic" and a "homicidal bloomin' maniac". (AUDIO: The Resurrection of Mars)

His TARDIS was his "pride and joy," (AUDIO: The Resurrection of Mars) and he would boast both about his plans and his TARDIS, and he enjoyed mocking the Doctor whenever they met. Indeed, when he met the Eighth Doctor on Deimos, the Monk took particular delight in taunting the Doctor for his failures despite him being involved in manipulating the situation so the Doctor would need to save Lucie from the Ice Warriors. (AUDIO: The Resurrection of Mars)

The Eighth Doctor compared the Monk to his previous self when he heard the story from Lucie of how the Monk had taken her to a planet to prevent the birth of a dictator by burying his parents under an avalanche that also destroyed the settlement. The Doctor pointed out that the Monk and his own past incarnation, the Seventh Doctor, were not too dissimilar; they both believed the ends justified the means for some "greater good," and how the Seventh Doctor had a similar mindset for devising masterplans while believing that the needs of the many outweighed the means of the few. (AUDIO: The Resurrection of Mars)

During a later encounter with the Monk when he discovered the other Time Lord was helping the Daleks re-conquer Earth in the 22nd century, the Doctor stated the Monk was "like a child, a dangerously powerful child," and he "needed to grow up. Fast." Tamsin Drew also claimed the Monk was a child before she learnt the truth of the Daleks' presence on Earth. The Doctor also claimed the Monk to be "out of his depth." (AUDIO: To the Death)

The "Abbot Thelonius" Monk's nature required him to reflect any responsibility and blame for his past actions onto anyone else, further exaggerating his blatant arrogance and fecklessness. (AUDIO: The Secret History)

The Monk often came across as a wannabe rather than a true villain or hero, with his greater plans and objectives fundamentally undermined by his own inability to recognise his limitations, such as participating in an alliance with the Daleks to conquer Earth because he believed that the Daleks would be defeated eventually. (AUDIO: To the Death) The consequences of his attitude were most clearly demonstrated when he was able to implement a complex plan that saw him taking the Doctor's place in the belief that he could be better than the Doctor, only for his former ally to see the future he would create and recognise that the Monk's active interference in history were making things worse than they would have been if the Doctor had been allowed to continue existing and adopting his usual pattern of stepping in during great danger but otherwise allowing people to make their own mistakes. (AUDIO: The Secret History)

Appearance and clothing
The "Abbot Thelonius" Monk resembled a short, balding older man with a broad face and green eyes. He largely rejected the monk's habit in favour of a tan coloured checked suit with a waist coat and a garish bow tie and pink shirt. (AUDIO: The Book of Kells)