Karma Kagyu, or Kamtsang Kagyu, is a widely practiced and probably the second-largest 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, with current centres in over 60 countries. The spiritual head of the Karma Kagyu is the Gyalwa Karmapa; the 2nd among the 10 Karmapas had been 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 Kagyu school, also transliterated as Kagyü, or Kagyud, which translates to "Oral Lineage" or "Whispered Transmission" school, is one of the main schools of Tibetan Buddhism. The Kagyu lineages trace themselves back to the 11th century Indian Mahasiddhas Naropa, Maitripa and the yogini Niguma, via their student Marpa Lotsawa (1012–1097), who brought their teachings to Tibet. Marpa's student Milarepa was also an influential poet and teacher.