- Language: Extremaduran
- Alternate names: Castúo, Cahtúo, Cahtúö
- Language code: dspax
- Language family: Indo-European, Italic, Romance, Italo-Western, Western, Gallo-Iberian, Ibero-Romance, West Iberian, Castilian
- Number of speakers:
- Script: Latin script
Castúo is the generic name for the dialects of Spanish spoken in the autonomous community of Extremadura, in Spain. It must not be confused with either Extremaduran, from Astur-leonese roots, or Fala, from Galician-Portuguese roots.