| Le Châtellier | |
| Native Name: | (Gallo) |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Saint-Pôtan (CôtesArmor).svg |
| Coordinates: | 48.4167°N -1.2528°W |
| Insee: | 35071 |
| Postal Code: | 35133 |
| Arrondissement: | Fougères-Vitré |
| Canton: | Val-Couesnon |
| Mayor: | Pierre Sourdin[1] |
| Term: | 2020 - 2026 |
| Elevation Min M: | 119 |
| Elevation Max M: | 183 |
| Area Km2: | 13.43 |
Le Châtellier (in French pronounced as /lə ʃatəlje/; Breton: Kasteller; Gallo: Le Chastelier) is a commune in the Ille-et-Vilaine Department in Brittany in northwestern France.
Inhabitants of Le Châtellier are called Castellérois or Castellégiens in French.
The Botanical garden of Upper Brittany is located in Le Châtellier.