长尾叶猴属（学名 Semnopithecus），猴科的一属，产于印度次大陆，目前认为包含七个物种：

Gray langurs or Hanuman langurs, the most widespread langurs of South Asia, are a group of Old World monkeys constituting the entirety of the genus Semnopithecus. All taxa have traditionally been placed in the single species Semnopithecus entellus. In 2001, it was recommended that several distinctive former subspecies should be given species status, so that seven species are recognized. A taxonomic classification with fewer species has also been proposed. Genetic evidence suggests that the Nilgiri langur and purple-faced langur, which usually are placed in the genus Trachypithecus, actually belong in Semnopithecus.