K'anpo Rimpoche was a wise Time Lord who, forsaking life on Gallifrey, decided to live the life of a Buddhist abbot on late 20th century Earth.
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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 the Doctor "a little push" enabling him regenerate into his next incarnation. (DW: Planet of the Spiders)