Trasmiras is a municipality in the province of Ourense, within the autonomous community of Galicia in northwestern Spain. It forms part of the comarca (district) of A Limia, a comarca located in the southern interior of Galicia.
As a municipality, Trasmiras is one of the local administrative units into which the province of Ourense is divided, and it belongs to the wider Galician regional structure alongside the other municipalities of A Limia. The area lies within the province of Ourense, the only landlocked province of Galicia.