The term Aussie Critter refers to three animals native to Australia: the KOALA (5 letters), the roo (3 letters), and the KANGAROO (8 letters). The KOALA is a marsupial mammal that lives in eucalyptus trees and is known for its cuddly appearance. The roo is a small, hopping marsupial that is often seen in the Australian outback. The KANGAROO is the largest marsupial and is well-known for its ability to hop great distances.