Pelayo is the Spanish form of the Latin name Pelagius. It may refer to:
- Pelagius of Asturias, founder of the Kingdom of Asturias and beginner of the Reconquista
- Pelagius of Córdoba, tenth-century Christian martyr
- Pelagius of Oviedo, bishop and chronicler
- Spanish battleship Pelayo, a battleship that served in the Spanish Navy from 1888 to 1925
- Ermita de San Pelayo y San Isidoro, a Romanesque hermitage that formerly was in Ávila, and whose ruins are now located in Madrid
- Pelayo, a synonym for the genus of South American spiders Josa
