Mahākāla is a deity common to Hinduism and Tantric Buddhism.  In Buddhism, Mahākāla is regarded as the sacred Dharmapāla (“Protector of the Dharma”), while in Hinduism, Mahākāla is a fierce manifestation of the Hindu god Shiva and the consort of the goddess Mahākālī; he most prominently appears in the Kalikula sect of Shaktism. Mahākāla also appears as a protector deity in Vajrayana, Chinese Esoteric, and Tibetan Buddhism (see Citipati), and also in the Chàn and Shingon traditions. He is known as Dàhēitiān and Daaih’hāktīn (大黑天) in Mandarin and Cantonese, Daeheukcheon (대흑천) in Korean, Đại Hắc Thiên in Vietnamese, and Daikokuten (大黒天) in Japanese.

Mahayana Buddhism, and all schools of Tibetan Buddhism, rely on Mahakala as guardian deity. He is depicted in a number of variations, each with distinctly different qualities and aspects. He is also regarded as the emanation of different beings in different cases, namely Avalokiteśvara (Wylie: spyan ras gzigs) or Cakrasaṃvara (Wylie: ’khor lo bde mchog). Mahakala is almost always depicted with a crown of five skulls, which represent the transmutation of the five kleśās (negative afflictions) into the five wisdoms.

The most notable variation in Mahakala’s manifestations and depictions is in the number of arms, but other details can vary as well. For instance, in some cases there are Mahakalas in white, with multiple heads, without genitals, standing on varying numbers of various things, holding various implements, with alternative adornments, and so on.

Mahākāla is mentioned in many Chinese Buddhist texts, although iconographic depictions of him in China were rare during the Tang and Song periods. He eventually became the center of a flourishing cult after the 9th century in the kingdoms of Nanzhao and Dali in what is now the province of Yunnan, a region bordering Tibet, where his cult was also widespread. Due to Tibetan influence, his importance further increased during the Mongol-led Yuan dynasty, with his likeness being displayed in the imperial palace and in Buddhist temples inside and outside the capital.