St. Mary's Roman Catholic Church, Newport is a historic church located at Newport, Charles County, Maryland. It was built about 1840, and converted for use as a parish hall in 1906. It is a rectangular brick structure, four bays in length and three bays wide. It is of simple architectural styling typical of the Greek Revival period in this locality. Located on the property is the church cemetery, which includes the burial plot of the Brent-Merrick family, including congressman William Duhurst Merrick (1793–1857). It has several impressively scaled and ornamented monuments enclosed within a decorative mid-19th century wrought iron fence. Other memorial stones bear the signature of "A. Geddess," who founded the long-active Geddess monument firm of Baltimore in 1822.