| Crossac | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason crossac44.svg |
| Arrondissement: | Saint-Nazaire |
| Canton: | Pontchâteau |
| Insee: | 44050 |
| Postal Code: | 44160 |
| Mayor: | Olivier Demarty[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Pays de Pont-Château - Saint-Gildas-des-Bois |
| Coordinates: | 47.4122°N -2.1669°W |
| Elevation Min M: | 0 |
| Elevation Max M: | 22 |
| Area Km2: | 25.85 |
Crossac (in French pronounced as /kʁɔsak/; Gallo: Croczac or Croça, Breton: Kroazieg) is a commune in the Loire-Atlantique department in western France.