Maitripa
Maitripa, also known by the names Maitrigupta, Maitripada or Advayavajra, became highly influential both in in the Great Way and in the Diamond Way.
It is through him that Maitreya's and Asanga's crucial work on buddha nature, the Uttara Tantra Shastra, became widespread in Tibet. He also transmitted the tantric aspect of buddha nature, embodied in the Mahamudra teachings, which treat the topic of mind in great detail and provide a wide range of progressive, highly refined meditations.