The Nilgiri tahr (Nilgiritragus hylocrius) is an ungulate that is endemic to the Nilgiri Hills and the southern portion of the Western and Eastern Ghats in the states of Tamil Nadu and Kerala in southern India. It is the state animal of Tamil Nadu. Despite its local name, it is more closely related to the sheep of the genus Ovis than the ibex and wild goats of the genus Capra. It is the only species in the genus Nilgiritragus.

The genus name Nilgiritragus is derived from the Tamil word Neelagiri meaning "blue hills" and the Greek word trágos meaning "goat".

Results of a phylogenetic analysis showed that the Nilgiri tahr forms a sister group with the genus Ovis and has been placed into the monotypic genus Nilgiritragus in 2005. It used to be placed in the genus Hemitragus together with the Himalayan tahr (H. jemlahicus) and the Arabian tahr (Arabitragus jayakari), which are both closer associated with the genus Capra.

The Nilgiri tahr is a stocky goat with short, coarse fur and a bristly mane. Males are larger than females and of darker colour when mature. Both sexes have curved horns, reaching up to 40 cm (16 in) for males and 30 cm (12 in) for females. Adult males weigh 80 to 100 kg (180 to 220 lb) and stand about 100 cm (39 in) tall at the shoulder. Adult males develop a light grey area on their backs, thus are called "saddlebacks".

The Nilgiri tahr can be found only in India. It inhabits the open montane grassland habitat of the South Western Ghats montane rain forests ecoregion. At elevations from 1,200 to 2,600 m (3,900 to 8,500 ft), the forests open into large grasslands interspersed with pockets of stunted forests, locally known as sholas. These grassland habitats are surrounded by dense forests at the lower elevations. The Nilgiri tahrs formerly ranged over these grasslands in large herds, but hunting and poaching in the 19th century reduced their population.

Nilgiri Tahr (Nilgiritragus hylocrius) - Eravikulum National Park Kerala India