A prehensile tail is the tail of an animal that has adapted to be able to grasp or hold objects. Fully prehensile tails can be used to hold and manipulate objects, and in particular to aid arboreal creatures in finding and eating food in the trees. If the tail cannot be used for this it is considered only partially prehensile - such tails are often used to anchor an animal's body to dangle from a branch, or as an aid for climbing. The term prehensile means "able to grasp" (from the Latin prehendere, to take hold of, to grasp).

One point of interest is the distribution of animals with prehensile tails. The prehensile tail is predominantly a New World adaptation, especially among mammals. Many more animals in South America have prehensile tails than in Africa and Southeast Asia. It has been argued that animals with prehensile tails predominate in South America as the forest is very dense compared to that of Africa or Southeast Asia. In contrast, in less dense forest such as in Southeast Asia it is observed that gliding animals such as colugos or flying snakes tend to be more common instead, whereas there are few gliding vertebrates in South America. Also South American rainforests tend to have more lianas as there are fewer large animals to eat them compared to Africa and Asia; the presence of lianas perhaps aiding climbers but obstructing gliders. Curiously, Australia-New Guinea contains many mammals with prehensile tails and also many mammals which can glide; in fact, all Australian mammalian gliders have tails that are prehensile to an extent.