Shadbhuja Mahakala (Tibetan: nag po chen po chag drug pa. English: the Great Black One with Six Hands), wrathful emanation of Avalokiteshvara.
"The Lord of Pristine Awareness has six hands and a body dark blue in colour. The first two hold a curved knife and skullcup, the middle two a human skull mala and trident, the lowest two a damaru drum and lasso. Adorned with a tiger skin, garland of heads, bones and snakes, and small bells on the hands and feet. Standing in a manner with the two legs together pressing down on Ganapati. With three eyes, bared fangs, eyebrows, beard and hair flowing upward with Akshobhya as a crown. Anointed with a sindhura drop on the forehead. Supported behind by a sandalwood tree, dwelling in the middle of a blazing mass of fire. On the [lower] left is Shri Devi, riding a mule, holding a stick and bag of disease. In front is yaksha Kshetrapala, reddish black, holding a curved knife and skullcup, riding a crazy black bear. At the right is Jinamitra, dark red, holding a hand drum and wheel. Behind [and above] is Takkiraja, black, holding a razor and blood filled skullcup. At the left is the lord of maras, Trakshe, holding a banner, and a skullcup to the heart, riding a black daemon horse with white hooves. He wears a long black silk cloak and boots. Outside of that sport the seventy-five great lords and an ocean of oath-bound ones together with retinue." (Jonang Taranatha, 1575-1634).
Lineage: Vajradhara, Jnana Dakini, shri Shavaripa, lord Maitripa, mahasiddha Rahulagupta, Khedrup Khyungpo Naljor (founder of the Shangpa Kagyu School, 11th century), Nyam Med Rinchen Tsondru, Bonton Kyergangpa (famous terton of the Hayagriva cycle of practice), etc.
Jeff Watt [added 8-2014]