In Vajrayana iconography and thangka depictions, dharmapālas are fearsome beings, often with many heads, many hands, or many feet. Dharmapālas often have blue, black or red skin, and a fierce expression with protruding fangs. Though dharmapālas have a terrifying appearance and countenance, they are all bodhisattvas or buddhas, meaning that they are embodiments of compassion that act in a wrathful way for the benefit of sentient beings.
In Tibet, the eight principal Dharmapalas are:
In Tibet, most monasteries have a dedicated dharmapāla which was originally comparable to a genius loci. The many forms of Mahakala, for example, are emanations of Avalokiteshvara (sometimes related to the Hindu god Shiva). Kalarupa and Yamantaka are considered emanations of the Buddha of Wisdom (Manjushri); and Shri Devi (Tib. Palden Lhamo).
The main functions of a dharmapāla are to avert the inner and outer obstacles that prevent practitioners from attaining spiritual realizations, as well as to foster the necessary conditions for their practice. Dharmapāla can be Buddhas, Bodhisattvas or Dharmarajas (Damchen in Tibetan). Only the dharmapālas that have realized shunyata are seen as an object of Buddhist refuge.
The Damchen were originally Tibetan mountain-spirits who were bound under oath to protect the Dharma by Padmasambhava and other Buddhist saints during the period of transmission of Buddhism from India to Tibet.