The mountain hawk-eagle (Nisaetus nipalensis) or Hodgson's hawk-eagle, is a large bird of prey native to Asia. The latter name is in reference to the naturalist, Brian Houghton Hodgson, who described the species after collecting one himself in the Himalayas. A less widely recognized common English name is the feather-toed eagle. Like all eagles, it is in the family Accipitridae. Its feathered tarsus marks this species as a member of the subfamily Aquilinae.
The mountain hawk-eagle is a large raptor and fairly large eagle. Although described not infrequently as "slim", it is usually perceptibly bulkier and more massive than most other members of its genus. It is seemingly the largest member of the 10 currently recognized species in the genus Nisaetus, notwithstanding the recently recognized Flores hawk-eagle (Nisaetus floris) (which was separated from the changeable hawk-eagle). The latter critically endangered island hawk-eagle seems to be of broadly similar size (weight is unknown), albeit with shorter wings, however the Flores species seems to be linearly outmatched by the largest mountain hawk-eagle. The mountain hawk-eagle attains a total length of 69 to 84 cm and a wingspan of 134 to 175 cm . Like most birds of prey, females are larger on average than the male, with a typical size difference of 3-8%, though it can rarely range up to a 21% difference. Although its wings are relatively short compared to eagles of open country, it has the longest wings of any of the hawk-eagles, even relative to their size. Mountain hawk-eagles have a short but strong bill, long and often erect crest (though can also be very short), short wings, a longish three-banded tail, feathered legs and powerful feet. It is usually rather unobtrusive, perching rather upright inside of canopy, with its wing-tips coming to less than one-fifth down the tail. There are two currently recognized races of the mountain hawk-eagle: the nominate subspecies (N. n. nipalensis) and the subspecies native to Japan (N. n. orientalis). The nominate race is found throughout mainland range and includes the likely dubious southeast Chinese races of N. n. fokiensis and N. n. whiteheadi.