Answer:
Contrary to popular belief, the koala is not a bear and is just referred to as a "koala" without the word bear. Koalas are marsupials, a subclass of the mammal group. Marsupials give birth to immature, or not fully developed, young, who then make their way to the mother's teat which is usually located in a pouch or pouch like appendage on the mother's abdomen.
The closest living relative of the koala is the wombat. Other marsupials include animals such the kangaroo, wallaby, Tasmanian devil, possum, quoll and bandicoot.
The reason why koalas and wombats are related is that they are both marsupials of the order Diprotodontia. The koala's family, Phascolarctidae, is closest to the wombat family, Vombatidae because they are both of the sub-order Vombatiformes.