Leg, Arm. toe, eye, ear, lip.
The word "did" is three letters long.
A large container name three letters long could be box or bin.
kangaroo, chipmunk, squirrel, antelope, elephant, thats all I can think of.
'Pan' is a Greek god whose name is only three letters long, the god of the Wild.
Isle of Man
There are two types of whales that have only three letters in their name. The Fin whale and the Sei whale.