The Hermit

A Gallifreyan hermit, by some accounts named the Hermit, (PROSE: Timewyrm: Revelation, Lucifer Rising) lived and meditated on the mountain behind the Doctor's house and tutored him during his early life. (TV: The Time Monster) By some accounts, this Time Lord was the same individual as K'anpo (PROSE: Gallifrey: A Rough Guide, Timewyrm: Genesys) or the One-Eyed One. (PROSE: Timewyrm: Revelation)

According to some accounts, the Hermit was an incarnation of the Time Lord known as K'anpo Rimpoche (TV: Planet of the Spiders) and Ansillon. (AUDIO: Blood of the Time Lords) By another account, he was an incarnation of Azmael. (TV: The Twin Dilemma)

Origins
According to one account, the Hermit was a member of a Gallifreyan religious order which had been disestablished during or shortly after the reign of Rassilon. It had fallen into decline by the time the Doctor was young. I.M. Foreman was another former monk. (PROSE: Interference)

Another account indicated he was hired as an ornamental hermit for the grounds of the House of Lungbarrow. (PROSE:Lungbarrow)

As the Hermit on Gallifrey
During the Doctor's early life, he knew the Hermit as a wise Time Lord who lived on the side of a mountain behind the house where the Doctor lived, (TV: The Time Monster, PROSE: Gallifrey: A Rough Guide) near the Prydonian Academy where he studied at the time. (PROSE: Timewyrm: Revelation) The Third Doctor said the Hermit spent "half his life" sitting under a tree behind the Doctor's childhood home. (PROSE: Separation Day)

The Hermit told stories to the young Gallifreyans, like the Doctor, about vampire swarms (TV: State of Decay) and the legions of the Sphinx. (PROSE: Lucifer Rising) He taught the Doctor transmigration. (PROSE: The Three Paths)

The Hermit was, as the Third Doctor later said, his guru. In the time of the Doctor's greatest despair, he showed him hope in a simple yellow flower (TV: The Time Monster) called a sarlain. (PROSE: Timewyrm: Revelation)

He would often act as an informal advisor to members of the Deca. (PROSE: Report on Term's Work)

Once, the Hermit told the Doctor to fast for three days and three nights to make supplications to the Menti Celesti. (PROSE: Timewyrm: Revelation) Towards the end of the Doctor's first life, the Hermit helped him prepare for his upcoming regeneration by telling him the story of Penultimate Evil and returning to him his Five Hundred Year Diary. (PROSE: The Three Paths)

Further activities
The Hermit spent several days communicating telepathically with to the Third Doctor, warning him of the Collision, and explained to him the events leading up to it. He told the Doctor to stop the chain of events at its source. (PROSE: Separation Day)

Later incarnations
By one account, the Third Doctor met the Hermit in England when he was using the title "K'anpo Rimpoche". While they fought Eight Legs, K'anpo and his future incarnation Cho-Je helped prepare the Doctor and his companions for his regeneration. (TV: Planet of the Spiders, PROSE: Doctor Who and the Planet of the Spiders) By one account, this Time Lord used the name Ansillon early and later in his life. (AUDIO: Blood of the Time Lords)

By another account, the Sixth Doctor's favorite mentor was Azmael, a renegade Time Lord who later left Gallifrey and became leader of the planet Jaconda. He died fighting Mestor with the Doctor. (TV: The Twin Dilemma) By another account, Azmael was instead the Doctor's tutor at the Prydonian Academy. (PROSE: Divided Loyalties)

Following the fall of Mictlan, one of the former Celestis – a hermit previously known as Investigator Four – wandered into the Nevada desert. (PROSE: The Taking of Planet 5)

The Sixth Doctor visited his old mentor at the end of his life, when he had used up all his regenerations. The Doctor stayed in his house until he died and bid him thanks and farewell. (PROSE: Gone Too Soon)

Legacy
In Mesopotamia, the Seventh Doctor would later try to apply the techniques that the Hermit had taught him to remember why his fourth incarnation had recorded a warning about the Timewyrm for his present self. (PROSE: Timewyrm: Genesys)