Trimley St. Mary is a parish and village on the outskirts of Felixstowe, on a low-lying peninsula between Harwich Harbour and the River Deben, in the East Suffolk district, in Suffolk, England. It lies on the Roman road between Felixstowe and Ipswich. Its eastern border is Spriteshall Lane. The village, and its neighbour Trimley St. Martin, are famous for their adjacent churches, which were built as the result of a historical family feud. St. Mary's church is the southerly church.