The Cat Ba Langur, also known as Golden-headed Langur (fig.), is a species of Leaf Monkey found only on the island of Cat Ba in Ha Long Bay (fig.).

Its body is mostly blackish to dark grey, with silvery flanks on the hips and upper legs, and a bright golden to yellowish-white head, shoulders and rump. It has a rather thick tail, that can measure up to 89 centimeters in length.