Thomasomys is a genus of rodent in the family Cricetidae, named after British zoologist Oldfield Thomas. Nuclear DNA sequence analysis has indicated that it is a sister taxon to Rhagomys. It contains the following species:
Anderson's Oldfield mouse (Thomasomys andersoni)Apeco Oldfield mouse (Thomasomys apeco)Golden Oldfield mouse (Thomasomys aureus)Beady-eyed mouse (Thomasomys baeops)Silky Oldfield mouse (Thomasomys bombycinus)White-tipped Oldfield mouse (Thomasomys caudivarius)Ashy-bellied Oldfield mouse (Thomasomys cinereiventer)Ash-colored Oldfield mouse (Thomasomys cinereus)Cinnamon-colored Oldfield mouse (Thomasomys cinnameus)Daphne's Oldfield mouse (Thomasomys daphne)Peruvian Oldfield mouse (Thomasomys eleusis)Wandering Oldfield mouse (Thomasomys erro)Slender Oldfield mouse (Thomasomys gracilis)Hudson's Oldfield mouse (Thomasomys hudsoni)Woodland Oldfield mouse (Thomasomys hylophilus)Inca Oldfield mouse (Thomasomys incanus)Strong-tailed Oldfield mouse (Thomasomys ischyrus)Kalinowski's Oldfield mouse (Thomasomys kalinowskii)Ladew's Oldfield mouse (Thomasomys ladewi)Soft-furred Oldfield mouse (Thomasomys laniger)Large-eared Oldfield mouse (Thomasomys macrotis)Unicolored Oldfield mouse (Thomasomys monochromos)Snow-footed Oldfield mouse (Thomasomys niveipes)Distinguished Oldfield mouse (Thomasomys notatus)Ashaninka Oldfield mouse (Thomasomys onkiro)Montane Oldfield mouse (Thomasomys oreas)Paramo Oldfield mouse (Thomasomys paramorum)Popayán Oldfield mouse (Thomasomys popayanus)Cajamarca Oldfield mouse (Thomasomys praetor)Thomas's Oldfield mouse (Thomasomys pyrrhonotus)Rhoads's Oldfield mouse (Thomasomys rhoadsi)Rosalinda's Oldfield mouse (Thomasomys rosalinda)Forest Oldfield mouse (Thomasomys silvestris)Taczanowski's Oldfield mouse (Thomasomys taczanowskii)Ucucha Oldfield mouse (Thomasomys ucucha)Dressy Oldfield mouse (Thomasomys vestitus)Pichincha Oldfield mouse (Thomasomys vulcani)
