Ash-colored Oldfield Mouse
Thomasomys cinereus
- Least concern
- Card rarity: Common
- Mammals

The ash-colored Oldfield mouse is a species of rodent in the genus Thomasomys. It is found in montane forests of the Department of Cajamarca in northern Peru, at elevations of 1,524 to 3,818 metres. Until 2023, it was thought to be more widely distributed, ranging into southern Ecuador, but these populations are now identified as three separate, closely related species, T. lojapiuranus, T. pagaibambensis, and T. shallqukucha.
Classification
- Class
- Mammalia
- Order
- Rodentia
- Family
- Cricetidae
- Genus
- Thomasomys