Mary Tavy is a village with a population of around 600, located four miles north of Tavistock in Devon in south-west England; it is named after the River Tavy. It used to be home to the world's largest copper mine Wheal Friendship, as well as a number of lead and tin mines. It borders Dartmoor National Park. The village lies a mile or two north of Peter Tavy; both were shown as separate settlements in the Domesday Book entry of 1086.
St Mary's Parish Church has a pinnacled west tower built of granite, a south porch with old wagon roof and a south transept built in 1893.