Dharmapala

A dharmapāla (Tibetan: ཆོས་སྐྱོང་ (), Chinese: 達磨波羅, 達摩波羅, , 護法鬼神, 諸天鬼神, 護法龍天, 諸天善神, ) is a type of wrathful god in Buddhism. The name means ""dharma" protector" in Sanskrit, and the "dharmapālas" are also known as the Defenders of the Justice (Dharma), or the Guardians of the Law. There are two kinds of "dharmapala", Worldly Guardians and Wisdom Protectors. Only Wisdom Protectors are enlightened beings.
Description.
A protector of Buddhist dharma is called a "dharmapala". They are typically wrathful deities, depicted with terrifying iconography in the Mahayana and tantric traditions of Buddhism. The wrathfulness is intended to depict their willingness to defend and guard Buddhist followers from dangers and enemies. The "Aṣṭagatyaḥ" (the eight kinds of nonhuman beings) is one category of "dharmapālas", which includes the Garuda, Deva, Naga, Yaksha, Gandharva, Asura, Kinnara and Mahoraga.
In Vajrayana iconography and thangka depictions, "dharmapala" are fearsome beings, often with many heads, many hands, or many feet. "Dharmapala" often have blue, black or red skin, and a fierce expression with protruding fangs. Although "dharmapala" have a terrifying appearance, they only act in a wrathful way for the benefit of sentient beings.
The devotional worship of "dharmapālas" in the Tibetan tradition is traceable to early 8th-century.
Tibetan Buddhism.
There are many different "dharmapalas" in Tibetan Buddhism. Each school has its own principle "dharmapalas" and most monasteries have a dedicated "dharmapāla" which was originally comparable to a genius loci. The many forms of Mahakala are emanations of Avalokiteshvara. Kalarupa and Yamantaka are considered by practitioners to be emanations of Manjushri the Bodhisattva of Wisdom. 
Principal wisdom protector "dharmapalas" include:
Other "dharmapalas" include:
The main functions of a "dharmapāla" are said to be to avert the inner and outer obstacles that prevent spiritual practitioners from attaining spiritual realizations, as well as to foster the necessary conditions for their practice.
Shingon Buddhism.
In Japanese Shingon Buddhism, a descendant of Tangmi, or Chinese Esoteric Buddhism, "dharmapālas" such as Acala and Yamantaka are classified as Wisdom Kings. Other "dharmapālas", notably Mahakala, belong to the Deva realm, the fourth and lowest class in the hierarchy of honorable beings.
Related deities.
In Tibetan Buddhism, there are two other classes of defender, the lokapālas and Kshetrapala Papiya, Guan Yu and Hachiman are also known as defenders.