Bon or Bön (Tibetan: བོན་, Wylie: bon, ZYPY: Pön, Lhasa dialect: [pʰø̃̀]), also known as Yungdrung Bon (Tibetan: གཡུང་དྲུང་བོན་, Wylie: g.yung drung bon, ZYPY: Yungchung Pön, lit. 'eternal Bon'), is the indigenous Tibetan religion which shares many similarities and influenced Tibetan Buddhism. It initially developed in the tenth and eleventh centuries but retains elements from earlier religious traditions. Bon is a significant minority religion in Tibet, especially in the east, as well as in the surrounding Himalayan regions.

The relationship between Bon and Tibetan Buddhism has been a subject of debate. According to the modern scholar Geoffrey Samuel, while Bon is "essentially a variant of Tibetan Buddhism" with many resemblances to Nyingma, it also preserves some genuinely ancient pre-Buddhist elements. David Snellgrove likewise sees Bon as a form of Buddhism, albeit a heterodox kind. Similarly, John Powers writes that "historical evidence indicates that Bön only developed as a self-conscious religious system under the influence of Buddhism".

Followers of Bon, known as "Bonpos" (Wylie: bon po), believe that the religion originated in a kingdom called Zhangzhung, located around Mount Kailash in the Himalayas. Bonpos hold that Bon was brought first to Zhangzhung, and then to Tibet. Bonpos identify the Buddha Shenrab Miwo (Wylie: gshen rab mi bo) as Bon's founder, although no available sources establish this figure's historicity.

Western scholars have posited several origins for Bon, and have used the term "Bon" in many ways. A distinction is sometimes made between an ancient Bon (Wylie: bon rnying), dating back to the pre-dynastic era before 618 CE; a classical Bon tradition (also called Yungdrung Bon – Wylie: g.yung drung bon) which emerged in the 10th and 11th centuries; and "New Bon" or Bon Sar (Wylie: bon gsar), a late syncretic movement dating back to the 14th century and active in eastern Tibet.

Tibetan Buddhist scholarship tends to cast Bon in a negative, adversarial light, with derogatory stories about Bon appearing in a number of Buddhist histories. The Rimé movement within Tibetan Buddhism encouraged more ecumenical attitudes between Bonpos and Buddhists. Western scholars began to take Bon seriously as a religious tradition worthy of study in the 1960s, in large part inspired by the work of English scholar David Snellgrove. Following the Chinese invasion of Tibet in 1950, Bonpo scholars began to arrive in Europe and North America, encouraging interest in Bon in the West. Today, a proportion of Tibetans – both in Tibet and in the Tibetan diaspora – practise Bon, and there are Bonpo centers in cities around the world.