The purple-faced langur, also known as the purple-faced leaf monkey, is a species of Old World monkey that is endemic to Sri Lanka. The animal is a long-tailed arboreal species, identified by a mostly brown appearance, dark face and a very shy nature. The species was once highly prevalent, found in suburban Colombo and the "wet zone" villages, but rapid urbanization has led to a significant decrease in the population level of the monkeys. It had traditionally been classified within the genus Trachypithecus but was moved to the genus Semnopithecus based on DNA evidence indicating that is it more closely related to the gray langurs.

Trachypithecus is a genus of Old World monkeys containing species known as lutungs, langurs, or leaf monkeys. Their range is much of Southeast Asia.