| Gave d'Ossau | |
| Map: | Gave d'Ossau.png |
| Source1 Location: | Pic du Midi d'Ossau |
| Mouth Location: | Gave d'Oloron |
| Mouth Coordinates: | 43.1947°N -0.6078°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | France |
| Length: | 48.5km (30.1miles) |
| Source1 Elevation: | 1008m (3,307feet) |
The Gave d'Ossau (in French pronounced as /ɡav dɔso/) is the torrential river flowing through the Ossau Valley, one of the three main valleys of the High-Béarn (Pyrénées-Atlantiques), in the Southwest of France.
It is formed in Gabas from the confluence of two gaves coming from both sides of the Pic du Midi d'Ossau:
After joining the Gave d'Aspe, in Oloron-Sainte-Marie, it forms the Gave d'Oloron. It is considered the upper course of the Gave d'Oloron by Sandre.
Throughout its length, the river is paralleled by the D934 road that runs from Pau to Spain, via the Col du Pourtalet.
In Castet, a dam forms the Lac de Castet.