| Tambre | |
| Map: | File:Hidrogalicia rio tambre.svg |
| Subdivision Type1: | Country |
| Subdivision Name1: | Spain |
| Subdivision Type2: | State |
| Subdivision Name2: | Galicia (Spain) |
| Length: | 134km (83miles) |
| Discharge1 Location: | Ponte Nafonso |
| Discharge1 Avg: | NaNlast1=Río Barja |
| Discharge1 Max: | 1160m3/s12 December 1989 |
| Source1: | Montes de Bocelo |
| Source1 Location: | Sobrado, A Coruña |
| Basin Size: | 1531km2 |
| Tributaries Left: | Mera, Sionlla |
| Tributaries Right: | Maruzo, Samo, Lengüelle, Dubra, Barcala |
The Tambre is a coastal river that crosses Galicia, in northwestern Spain. Its basin covers 1531km2.
The river flows through the province of A Coruña; the municipalities along its course are Sobrado, Curtis, Vilasantar, Boimorto, Mesía, Frades, Arzúa, O Pino, Oroso, Ordes, Trazo, Tordoia, Santiago de Compostela, Val do Dubra, Ames, A Baña, Brion, Negreira, Outes, Mazaricos, Noia and Lousame. Its mouth forms the Ría de Muros e Noia estuary.
It has been designated a Site of Community Importance.
In ancient times it was called Támaris, its name being related to that of the River Tamar in Cornwall. It was from the lands north of this river that the Spanish County of Trastámara and the royal House of Trastámara derive their name (Tras-Támara meaning "across the Tambre"). Tamarix may derived its name from the river.