| Castillon-Massas | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Castillon-Massas (Gers).svg |
| Arrondissement: | Auch |
| Canton: | Gascogne-Auscitaine |
| Insee: | 32089 |
| Postal Code: | 32360 |
| Mayor: | Bernard Carrera[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Grand Auch Cœur Gascogne |
| Coordinates: | 43.7203°N 0.5447°W |
| Elevation M: | 204 |
| Elevation Min M: | 136 |
| Elevation Max M: | 264 |
| Area Km2: | 9.59 |
Castillon-Massas (in French pronounced as /kastijɔ̃ masas/; Occitan (post 1500);: Castilhon de Massàs) is a commune in the Gers department in southwestern France.