Pig-tailed langur
Picture taken from the island of Siberut, off the west coast of Sumatra.
Author: Sam Morton https://www.flickr.com/photos/sammortonwildlifephotography/
Source: https://www.flickr.com/photos/sammortonwildlifephotography/6991641168/

The pig-tailed langur (Simias concolor), monotypic in genus Simias, is a large Old World monkey, endemic to several small islands off the coast of Sumatra in Indonesia. Its face is black, its fur is blackish-brown and it has a relatively short tail. It is a diurnal species, feeding in small groups in the rainforest canopy on leaves, and to a lesser extent, fruit and berries.