The fat-tailed dunnart is a species of mouse-like marsupial of the Dasyuridae, the family that includes the little red kaluta, quolls, and the Tasmanian devil.

The Dasyuridae are a family of marsupials native to Australia and New Guinea, including 71 extant species divided into 17 genera. Many are small and mouse-like or shrew-like, giving some of them the name marsupial mice or marsupial shrews, but the group also includes the cat-sized quolls, as well as the Tasmanian devil. They are found in a wide range of habitats, including grassland, underground, forests, and mountains, and some species are arboreal or semiaquatic. The Dasyuridae are often called the 'marsupial carnivores', as most members of the family are insectivores.