The Cinderella fat-tailed mouse opossum (Thylamys cinderella) is a species of opossum in the family Didelphidae.

[2] It is found in northern Argentina and southern Bolivia, in the eastern foothills of the Andes.

Its ventral fur is gray-based, except for the white to yellowish chest hairs.

It has been distinguished from T. sponsorius by the well-developed postorbital ridges of the latter,[3] but mitochondrial DNA sequence analysis does not support separate species status for sponsorius.

[1][4] This article about a marsupial is a stub.