Megalomys is a genus of rodent in the family Cricetidae, part of the tribe Oryzomyini. The genus contains five large rodents from various Caribbean islands, all of which are now extinct. The last species to survive was M. desmarestii from Martinique, which became extinct after the Mount Pelée eruption in 1902.

Temporal range: Middle Pleistocene-Late Holocene
Megalomys desmarestii Gervais.png
Megalomys desmarestii
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Subfamily: Sigmodontinae
Tribe: Oryzomyini
Genus: Megalomys
Trouessart, 1881

Megalomys audreyae
Megalomys curazensis
Megalomys desmarestii
Megalomys georginae
Megalomys luciae

It contains the following species: