The white-headed langur (Trachypithecus poliocephalus) is a critically endangered langur. Two subspecies are recognized: T. p. poliocephalus in Cát Bà Island, Vietnam, and T. p. leucocephalus in Guangxi, China. The former (the nominate subspecies), often known as the golden-headed or Cat Ba langur, is among the rarest primates in the world, and possibly the rarest primate in Asia, with population size estimated at less than 70 individuals.