The single species S. entellus has a head and body length of 410-780 mm and tail length of 690-1,080 mm. Weights range between 5.4-23.6 kg. Coloration of S. entellus is gray, brown or buff with yellowish, white, or orange-white underparts and crown. There is a prominent brow ridge and the fur grows downward over the brow, whorling at the front of the head and then back over the crown. Newborn langurs are blackish brown.

S. entellus is adaptable to a variety of environments and elevations. Habitats include desert edge, wet tropical forest, and alpine scrub, from sea level to 4,000 meters. It is extremely agile when traveling through trees, but adapts easily to areas where trees are scarce, walking or running on the ground using all four feet. Horizontal leaps of 3-5 meters are achieved easily in the trees and up to 13 meters can be covered with some loss of height. S. entellus is primarily vegetarian, as are other langurs, and forages in the early morning and later afternoon. Sleeping is done during midday. Leaves make up the major part of the langur’s diet, but fruits, flowers, and cultivated crops are also eaten when available.

Social groups have one of two structures: all male groups consisting of 2-32 individuals which include adults, subadults and a few juveniles, and heterosexual groups which may have only one adult male and average 50125 individuals. There is an exception to the latter structure. When populations are below carrying capacity of the environment, there may be more than one adult male present. Generally the ratio of adult females to adult males in these groups is 2:1. Dominance hierarchy in all male groups is established through fighting, and once resolved, intragroup coexistence can be stabilized. New groups may be formed by younger males reaching sexual maturity and establishing their own group with adult females from this same group they are leaving. The dominant male defends and leads the group. Vocalization seems to be limited to an early morning booming whoop done in chorus and which is thought to identify the location of a group. Though primarily peaceful, males from outside a group have been known to challenge the leader of a specific group and, if he wins, may kill all of the infants in his new group. Consequently, the fertile females are brought into estrus within 2 weeks and the new dominant male can establish his own lineage.

Births can occur any time of year, but are mostly concentrated during the dry season in India. In northern India this is April - May, and December - March in southern India. There is a 24 day estrous cycle and gestation is from 190-210 days. If an infant is lost, the female may go into estrous again in as soon as 8 days. Usually there is one offspring, but there is an are in the Himalayas where twins are frequently produced. Infants are weaned at about 10-12 months, sexual maturity is reached at 3-4 years for females and 6-7 years for males. Captive langurs have been recorded to live beyond age 25.

S. entellus is found in Pakistan and India, lowlands north of Godavari and Krishna Rivers, south of Ganges.