| Type: | municipality |
| Official Name: | Castillazuelo |
| Area Total Km2: | 15 |
| Elevation M: | 368 |
| Population Density Km2: | auto |
| Utc Offset: | +1 |
| Utc Offset Dst: | +2 |
Castillazuelo is a municipality located in the province of Huesca, Aragon, Spain. According to the 2018 census (INE), the municipality has a population of 169 inhabitants.