The Nicobar Long-tailed Macaque (Macaca fascicularis umbrosa, popularly known as the Nicobar Monkey) is a subspecies of the Crab-eating Macaque (M. fascicularis), endemic to the Nicobar Islands in the Bay of Bengal. This primate is found on three of the Nicobar Islands — Great Nicobar, Little Nicobar and Katchal Island, in biome regions consisting of Tropical and subtropical moist broadleaf forests.