| Cega | |
| Map: | Cega (rivière).png |
| Mouth: | Douro |
| Mouth Location: | Province of Valladolid |
| Subdivision Type1: | Country |
| Subdivision Name1: | Spain |
| Length: | 133km (83miles) |
| Source1: | Sierra de Guadarrama |
| Source1 Location: | Province of Segovia |
| Source1 Coordinates: | 41.0153°N -3.8511°W |
| Mouth Coordinates: | 41.5492°N -4.7675°W |
The Cega is a river in the Iberian Peninsula a left-bank tributary of the Douro.
It is born out of the confluence of the Artiñuelo and the Vueltas creeks in the Sierra de Guadarrama.[1] 133 km-long,[2] the Cega, running northwest through the province of Segovia, empties in the Douro in the province of Valladolid, having previously received the waters of the Pirón, its main left-bank tributary.