Karma Kagyu (Tibetan: ཀརྨ་བཀའ་བརྒྱུད, Wylie: karma bka'-brgyud), or Kamtsang Kagyu (Tibetan: ཀརྨ་ཀཾ་ཚང་, Wylie: kar+ma kaM tshang), is probably the 2nd largest and certainly the most widely practiced lineage within the Kagyu school, one of the four major schools of Tibetan Buddhism. The lineage has long-standing monasteries in Tibet, China, Russia, Mongolia, India, Nepal, and Bhutan, and current centers in at least 62 countries. The spiritual head of the Karma Kagyu is the Gyalwa Karmapa, and the 2nd through the 10th Karmapas were the principal spiritual advisors to successive Emperors of China. The Karma Kagyu are sometimes called the "Black Hat" Lamas, in reference to the Black Crown worn by the Karmapa.
The Karma Kagyu was founded by Düsum Khyenpa, 1st Karmapa Lama. It is headed by the Karmapa, a reincarnate lama (tulku). Followers believe that the Karmapa's appearance as the first historical consciously reincarnate teacher was predicted by Gautama Buddha in the Samadhiraja Sutra.