K'anpo Rimpoche was a wise Time Lord who, forsaking life on Gallifrey, decided to live the life of a Buddhist abbot on Earth.
Profile
The Doctor first met K'anpo Rimpoche as a wise hermit who lived on the side of a mountain in southern Gallifrey. He acted, for lack of a better word, the Doctor would later say, as his guru. In the time of the Doctor's greatest despair, he showed him hope in a simple daisy. (DW: The Time Monster, NA: Timewyrm: Revelation)
Next the Doctor met him as the abbot of a Buddhist meditation centre located in England with his assistant Cho Je. It seems that Cho Je only existed as a future projection of the K'anpo Rimpoche or a creation of his mind. Upon K'anpo Rimpoche's regeneration, he assumed Cho Je's form.
When the Doctor himself began to die as a result of the radiation from the Great One's cave, K'anpo Rimpoche teleported into the room in order to give his regeneration "a little push". (DW: Planet of the Spiders)