The Karmapa (honorific title His Holiness the Gyalwa Karmapa, sometimes spelled Gyalwang Karmapa) is the head of the Karma Kagyu, the largest sub-school of the Kagyupa (Tibetan Bka' brgyud), itself one of the four major schools of Tibetan Buddhism.
The historical seat of the Karmapas is Tsurphu Monastery in the Tolung valley of Tibet. His Holiness' principal seat in exile is the Dharma Chakra Centre at Rumtek Monastery in Sikkim, India. His regional monastic seats are Karma Triyana Dharmachakra in New York, Dhagpo Kagyu Ling in France and Tashi Choling in Bhutan.
Due to a controversy within the Karma Kagyu school over the recognition process, the identity of the current 17th Karmapa is disputed. See Karmapa controversy for details.
Read more about Karmapa: Origin of The Lineage, Black Crown, List of Previous Karmapas