Big deer mouse

{{Short description|Species of rodent}}

{{speciesbox

| name = Big deer mouse

| status = NT | status_system = IUCN3.1

|status_ref ={{cite iucn |author=Roach, N. |author2=Naylor, L. |date=2019 |title=Peromyscus grandis |volume=2019 |page=e.T16662A22359831 |doi=10.2305/IUCN.UK.2019-1.RLTS.T16662A22359831.en |access-date=14 November 2021}}

| genus = Peromyscus

| species = grandis

| authority = Goodwin, 1932

| synonyms =

}}

The big deer mouse, big deermouse, or giant deermouse (Peromyscus grandis) 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.