Quokka

Most marsupials live in Australia, constraining their range a bit already. But the quokka is only found in the southwest corner of Australia and a few nearby islands, giving it an even smaller area to live than its cousins.

Quokkas are fearless and curious of humans, which can lead to some unfortunate interactions with less-than-kind humans who come into contact with these puffy cheeked critters. Even some more altruistic people can mess up a quokkas life by feeding them. The quokka survives on vegetation not just for food, but for water.

Interestingly, the quokka has taken root in Two Peoples Bay Nature Reserve, a reserve initially set up to protect noisy scrub-birds. Since then, the Gilbert's potoroo has taken root. This species is possibly the most endangered marsupial in the world. Thus, one of the most vulnerable marsupials lives among one of the most endangered.