The gaur (Bos gaurus), also called Indian bison, is a large bovine native to South Asia and Southeast Asia. The species is listed as vulnerable on the IUCN Red List since 1986 as the population decline in parts of the species' range is likely to be well over 70% over the last three generations. Population trends are stable in well-protected areas, and are rebuilding in a few areas which had been neglected.

The word gaur is pronounced  /ˈɡaʊər/.

The gaur is the largest species of wild cattle, bigger than the African buffalo, the extinct aurochs, and wild water buffalo. The domesticated form of the gaur, Bos frontalis, is called gayal or mithun.

The Malayan gaur is called seladang, and the Burmese gaur is called pyoung.

The gaur is an extremely large mammal. It has a head-and-body length of 250 to 330 cm (8.2 to 10.8 ft), not counting a 70 to 105 cm (28 to 41 in) long tail, and is 165 to 220 cm (5.41 to 7.2 ft) high at the shoulder. The average weight is 650 to 1,000 kg (1,400 to 2,200 lb), with an occasional large bull weighing up to 1,500 kg (3,300 lb). Males are about one-fourth larger and heavier than females.