Padmasambhava
Padmasambhava was the High Lama of Det-Sen Monastery.
Padmasambhava met the Second Doctor when he visited the monastery in 1630. While travelling on the astral plane, he encountered the Great Intelligence, which took control of him as part of its plan to gain corporeal existence on Earth. He used his rank in the monastery to have tasks completed for the Intelligence. He hypnotised Songsten and Victoria Waterfield. When he was able to speak with his own voice, he tried to keep the monks safe and wanted them to flee the monastery.
In 1935, Padmasambhava finally died when the Intelligence was expelled by the Doctor, having lived over three hundred years. (TV: The Abominable Snowmen)
Although his body died, he carried on to the astral plane, where Thomni eventually encountered him and learned many of Padmasambhava's secrets. In October 1969, Padmasambhava became aware of Owain Vine, and his connection to the Great Intelligence. In the following months, from the astral plane, Padmasambhava nudged Owain on his journey via his meditations until, in January 1970, he finally revealed himself to Owain on the astral plane. There he explained to Owain who he really was, and how he first came to be the High Lama of Det-Sen. (PROSE: Night of the Intelligence)