Big Deer Mouse
Peromyscus grandis
- Near threatened
- Card rarity: Uncommon
- Mammals

The big deer mouse, big deermouse, or giant deermouse is a species of rodent in the family Cricetidae. It is a species of the genus Peromyscus, a closely related group of New World mice often called "deermice". It is endemic to Guatemala.
Classification
- Class
- Mammalia
- Order
- Rodentia
- Family
- Cricetidae
- Genus
- Peromyscus