Ratt

Ratts were a species that could morph between a rondent and humanoid form. (PROSE: At Childhood's End)

Biology
The Ratts', when in a bipedal form, had large, round black eyes and small mouths. They had large folds of skin stretched over their heads, giving the appearance that they were wearing hoods, and were around four tall. (PROSE: At Childhood's End)