| Official Name: | Castrillo de la Guareña |
| Pushpin Map: | Spain |
| Pushpin Map Caption: | Spain |
| Subdivision Name3: | La Guareña |
| Leader Title: | Mayor |
| Leader Name: | Ana María González Santos |
| Area Total Km2: | 21.91 |
| Population Demonym: | Castrillejos |
| Population Density Km2: | auto |
| Utc Offset: | +1 |
| Utc Offset Dst: | +2 |
| Coordinates: | 41.2303°N -5.3236°W |
Castrillo de la Guareña is a municipality located in the province of Zamora, Castile and León, Spain.