Thetford Priory is a Cluniac monastic house in Thetford, Norfolk, England.
One of the most important East Anglian monasteries, it was founded in 1103 by Roger Bigod, 1st Earl of Norfolk, and dedicated to Our Lady. In the 13th century, the Virgin Mary is said to have appeared in a vision to locals requesting the addition to the site of a Lady Chapel. During its construction, the old statue of her on the site was discovered to have a hollow in its head concealing saints' relics, and became a magnet for pilgrims.