The surilis are a group of Old World monkeys and make up the entirety of the genus Presbytis. They live on the southern portion of the Malay peninsula, on Sumatra, Borneo, Java and smaller nearby islands.

Surilis are rather small, slim built primates. Their fur at the top is brown, grey or black and at the lower surface whitish, sometimes also orange, with some species having fur designs at the head or at the hips. Their German name of "capped langur" comes from the hair on its head, which forms a tuft. It differs from the other langurs by characteristics in the shape of their head (particularly the lack of bulges above the eyes), in the teeth and by the size of their small thumbs. Surilis range in adult length from 40 to 60 cm (with a 50 to 85 cm long tail) and a weight of 5 to 8 kg.

Diurnal forest dwellers, they spend nearly their entire life in the trees. They live predominantly in groups of six to eight animals consisting of a male, several females, and their young. More recently they have been observed in monogamous pairings (particularly the Mentawai Langur), although this might be a reaction to the decrease of their habitat. The groups are hierarchically developed, with intergroup communication that is both vocal and postural.

The surilis' diet consists of leaves, fruits, and seeds.

Gestation time is five to six months, and births are typically of single young. Newborn animals are white colored and have a black strip at the back, although some have a cross-shaped mark. By one year the young are weaned and at an age of four to five years they are fully mature. Their life expectancy is estimated at 20 years.