Margaretamys is a genus of rodent in the family Muridae endemic to the island of Sulawesi in Indonesia. Up until 1973, it was known from only few examples of one species. Then Guy G. Musser collected more examples of this species during his stay in Sulawesi, as well as collecting two new species. And in 1981, as part of his huge project of sorting through the then very large genus Rattus, he described these as members of the new genus, Margaretamys.