St Michael Caerhays (Cornish: Lannvihal) is a civil parish and village in Cornwall, England, United Kingdom. The village is about seven miles (11 km) south-southwest of St Austell. The population at the 2011 census was 96
The ecclesiastical parish was a chapelry of St Stephen in Brannel until 1832. From the 16th century the Rectors of St Stephen resided here so the church of St Michael came to be regarded as the mother church. The church is Norman but the Lady Chapel was added in the 15th century by the Trevanions and it contains their monuments. Their home was on the site of Caerhayes Castle.
Caerhays Castle, a picturesque castellated mansion, is situated half-a-mile south of the village and was built by John Nash for J. B. Trevanion in 1808.