The Hog Deer (Hyelaphus porcinus) is a small deer whose habitat ranges from Pakistan, through northern India, to mainland southeast Asia. There are two subspecies of hog deer: Hyelaphus porcinus porcinus which inhabits much of the Indo-Gangetic Plains of Pakistan, northern India, Nepal, Bangladesh, southwestern Yunnan Province in China, all the way to western Thailand. Hyelaphus porcinus annamiticus that inhabits Thailand, and Indochina. Introduced populations also exist in Australia, the United States and Sri Lanka.

The hog deer gets its name from the hog-like manner in which it runs through the forests with its head hung low so that it can duck under obstacles instead of leaping over them like most other deer. Cover is taken as soon as it is feasible. During flight, the tail is held erect, showing the white underside.

A mature hog deer stag stands about 70 cm at the shoulder and weighs approximately 50 kg while hinds are much smaller, standing about 61 cm and weighing in the vicinity of 30 kg. They are very solidly built with a long body and relatively short legs and the line of the back slopes upward from the shoulders to a high rump. The ears are rounded; older animals tend to become light coloured in the face and neck.

Hog may refer to:

Deer (singular and plural) are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, mule deer such as black-tailed deer, elk, moose, red deer, reindeer (caribou), fallow deer, roe deer and chital. Male deer of all species (except the Chinese water deer) and also female reindeer grow and shed new antlers each year. In this they differ from permanently horned animals such as antelope; these are in the same order as deer and may bear a superficial resemblance. The musk deer of Asia and water chevrotain (or mouse deer) of tropical African and Asian forests are not usually regarded as true deer and form their own families, Moschidae and Tragulidae, respectively.

The word "deer" was originally broad in meaning, but became more specific over time. In Middle English der (Old English dēor) meant a wild animal of any kind. This was as opposed to cattle, which then meant any sort of domestic livestock that was easy to collect and remove from the land, from the idea of personal-property ownership (rather than real estate property) and related to modern chattel (property) and capital. Cognates of Old English dēor in other dead Germanic languages have the general sense of "animal", such as Old High German tior, Old Norse djur or dȳr, Gothic dius, Old Saxon dier, and Old Frisian diar.