The giant muntjac, sometimes referred to as the large-antlered muntjac, is the largest muntjac species and was discovered in 1994 in Vũ Quang, Hà Tĩnh Province of Vietnam and in central Laos. During inundation of the Nakai Reservoir in Khammouane Province of Laos for the Nam Theun 2 Multi-Purpose Project, 38 giant muntjac were captured, studied, and released into the adjacent Nakai-Nam Theun National Protected Area. Subsequent radio-tracking of a sample of these animals showed the relocation was successful. The species is also located in parts of eastern Cambodia, as well as the Annamite Mountains (Trường Sơn Mountains).

The giant muntjac is commonly found in evergreen forests and weighs about 30–50 kg. It has a red-brown coat and is an even-toed ungulate. Due to slash-and-burn agriculture, combined with hunting, the giant muntjac is considered critically endangered. It is preyed upon by animals such as the tiger and leopard. It is most closely related to Muntiacus muntjak (common muntjac).

It is classed as critically endangered