Guru Dragpo, originating in the 'Revealed Treasure' Tradition of the Nyingma School of Tibetan Buddhism, is a wrathful meditational form of Padmasambhava.
Although technically a guruyoga practice the function of Guru Dragpo is that of an ishtadevata (meditational deity).
In the Nyingma Tradition, following after the early meditational deities of the Guhyagarbha Tantra and Eight Heruka this practice of Guru Dragpo is possibly the most popular and the most represented in art.
In the 16th century the teacher Pema Karpo popularized a variation on Guru Dragpo called Guru Dragpur - principally practiced in the Drugpa Kagyu School.
Guru Dragpo, a wrathful form of Guru Rinpoche, is a fierce protector of the Dharma and a destroyer of obstacles on the path to enlightenment.
This practice is especially beneficial for transforming negative conditions into wisdom light.
Guru Dragpo Mantra
OM AH HUNG ATSIK NIRTSIK NAMO BHAGAWATE HUNG HUNG AH HUNG HUNG PHAT
The meditational deities of the Nyingma can be divided into three principal categories of deities.
The first are those deities described in the  Guhyagarbha Tantra. The second category are the Eight Heruka including Mahottara.
The third category are all of those forms that are included in the 'Revealed Treasure' Tradition (terma).
Many 'Revealed Treasures' are simply variations on the forms of the Guhyagarbha and Eight Heruka, however an entirely new group developed which are based on the being of Padmasambhava.
This third group includes deities such as the Outer, Inner and Secret Forms of Padmasambhava which include Guru Dragpo, Simhamukha and many others.
Forms & Types of Guru Dragpo:
1. Single (one face, two arms)
2. Single (with consort)
3. Heruka (three faces, six arms, consort)
4. Karma Guru Heruka (without consort)
5. Tarig Terma Tradition (with consort)