The most endangered monkey might depend upon the list you review, particularly since many lists include all primates and population statistics might not exist. Here are some where the situation appears dire:

• Miss Waldron's Red Colobus has not been seen since 1993 and may already be extinct.
• Variegated Spider Monkeys have had most of their habitat destroyed. Population unknown.
• In 2007, the population of the Golden-headed Langur was up to 65 from 53 in 2000.
• The Roloway Monkey is endangered and has even disappeared from protected area. Population unknown.

Three species of Mangabey monkeys are on the endangered list with each seeming to have a population of at least 1000. Some other species are threatened.

Snow Monkeys are not endangered, though their numbers have dropped.