| Castelviel | |
| Commune Status: | Commune |
| Arrondissement: | Langon |
| Canton: | Le Réolais et Les Bastides |
| Insee: | 33105 |
| Postal Code: | 33540 |
| Mayor: | Christiane Fouilhac[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 44.6683°N -0.1519°W |
| Elevation M: | 110 |
| Elevation Min M: | 53 |
| Elevation Max M: | 121 |
| Area Km2: | 8.02 |
Castelviel (in French pronounced as /kastɛlvjɛl/; Occitan (post 1500);: Castèthvièlh) is a commune in the Gironde department in Nouvelle-Aquitaine in southwestern France.