This is the largest living prosimian. The body is thickly covered with long, silky fur above, which becomes shorter beneath. Coloration is usually patterns of grays, browns, and blacks, but there is variation.
Some individuals are black, while others are almost or entirely white.
The head, ears, shoulders, back, and arms are usually black. On the rump there is a large triangular patch of white, usually surrounded by black. The great toe is long and opposable, and the remaining toes are joined by a web as far as the ends of the first joint. The muzzle is small and nearly naked, the eyes are large, and the skin is black. Females have two mammae.