Muntjacs are relatively small deer currently restricted, except for the Philippine and Wallacean subregions, to the Indomalayan region (Corbet and Hill, Mammals of the Indomalayan Region: A systematic review. Natural History Museum Publications and Oxford University Press, 1992). In the English language these deer have been interchangeably referred to as both muntjacs and barking deer. The former is a derivative, via the Dutch usage of muntjak, of a native Javanese language (Van Bemmel, Beaufortia 2:1–50, 1952)) as commemorated in the scientific names erected by Zimmermann (Enthaelt ein vollstaendiges Verzeichniss aller bekannten Quadrupeden. Weygandschen Buchhandlung, 1780) and Rafinesque (Analyse de la nature ou Tableau de l’univers et des corps organisés. Aux dépens de l’auteur, 1815), and the latter was derived from their dog-like “barking” vocalisations. This chapter covers various aspects of the biology and natural history of the Muntiacus genera, including taxonomy, descriptive notes, diversity, distribution, habitat and status in the wild. The chapter includes at least one or more photos of the species and a list of key literature.