The Mandrill (Mandrillus sphinx) is a primate of the Cercopithecidae (Old-world monkeys) family, closely related to the baboons and even more closely to the Drill. Both the Mandrill and the Drill were once classified as baboons in genus Papio, but recent research has determined that they should be separated into their own genus, Mandrillus. The Mandrill is the world's largest species of monkey.