Also known as the greater Malay Chevrotain and the Napu, it is an even toed ungulate (in the Tragulidae family). It lives in Sumatra, Borneo and some of the smaller islands of Indonesia and Malaysia, along with Myanmar, Soutehrn Thailand and the Malaysian mainland. 

It is naturally found in subtropical and tropical , moist lowland forest.

Despite the name, mouse-deer are not true deer, and it is only greater in comparison to the other mouse-deer in its family which are smaller. It weighs 5-8kg and measures up to 75cm long (the williamson mouse-deer can grow to similar size). Its shoulder is roughly 30-35cm tall. Its legs can be as thin as a pencil. Like other mouse-deer, it does not have antlers, but instead males have canines which extend beyond the mouth, essentially small tusks.

They are found on Sumatra, Borneo, and smaller Malaysian and Indonesian islands, and in southern Myanmar, southern Thailand, and peninsular Malaysia and live near water, in tropical forests and mangrove thickets. They were thought to be locally extinct in Singapore, but were rediscovered on an offshore island in 2008. Readily confused with several other species, reports of them outside areas above are probably mistaken identity. They are land animals, but spend time in wet, swampy areas.