Member of some species of the order Chelonia (turtles and tortoises). Terrapins are small to medium-sized, aquatic or semi-aquatic, and are found widely in temperate zones. They are omnivorous, but generally eat aquatic animals. Some species are in danger of extinction owing to collection for the pet trade; most of the animals collected die in transit.

Species include the diamondback terrapin Malaclemys terrapin of the eastern USA, the yellow-bellied terrapin, and the red-eared terrapin Pseudemys scripta elegans.