The maroon langur, maroon leaf monkey, or red leaf monkey (Presbytis rubicunda) is a species of primate in the Cercopithecidae family. It is found on the southeast Asian island of Borneo and the nearby smaller Karimata. P. rubicunda mostly live in forests at altitudes below 2,000 m. They feed on leaves (36%), seeds (30%) and fruits (34%) and may explore more than 100 plant species during one year.