St Giles on the Heath, sometimes hyphenated as St Giles-on-the-Heath, is a village and civil parish in the far west of Devon, England. It forms part of the local government district of Torridge. The village is in the east of the parish and lies on the A388 road about eight miles south of the town of Holsworthy. The parish is surrounded clockwise from the north-west by the parishes of Northcott, Luffincott, Ashwater, Virginstow, Broadwoodwidger and Lifton. Its western border follows the River Tamar which forms the county boundary with Cornwall. In 2001 its population was 617, significantly higher than the 258 residents it had in 1901.The village is part of Broadheath electoral ward.
Before 1193 the church of St Giles was a chapelry of North Petherwin belonging to the abbey of Tavistock. However from 1288 it was a chapelry of St Stephen’s by Launceston belonging to Launceston Priory. In 1500 the relationship between the two churches was settled; St Giles chapel was granted the right of burial and was thereafter to be served by a chaplain maintained by the priory who also served the chapel of Werrington. At the Reformation it became a donative. The parish was originally in Cornwall, and one of the few Cornish places on the east of the river Tamar, but is now part of the county of Devon. Its hamlets include Panson, Hoggadon, and Sitcott.
The parish of St Giles belonged before 1876 to the Archdeaconry of Cornwall and was then included in the new Diocese of Truro to which it still belongs. St Giles-in-the-Heath forms part of Werrington with St Giles-In-The-Heath and Virginstow United Parish; the benefice is united with the benefices of Boyton and North Tamerton. One family of note to hail from St. Giles are the Devonshire family of Cary who originated here in the 12th century at Carey Barton and there is a mural monument to the family in the church. West Panson was mentioned in the Domesday survey.