St. Marys is a civil parish in County Westmeath, Ireland.

St. Mary's is the sole civil parish in the barony of Brawny in the province of Leinster.

St. Mary's civil parish comprises part of the town of Athlone, the village of Ballykeeran and 62 townlands: Aghacocara, Ankersbower, Ardnaglug, Athlone, Ballygowlan, Ballykeeran, Blyry Lower, Blyry Upper, Bunnahinly, Bunnavally, Cannonsfield, Cappankelly, Carrickobreen, Cartrontroy, Cloghanboy (Cooke), Cloghanboy (Homan), Cloghanboy (Strain), Cloghanboy West, Clonagh, Clonbrusk, Cloonbonny, Cloondalin, Collegeland, Cookanamuck, Coosan, Cornamaddy, Cornamagh, Corralena, Creaghduff, Creaghduff South, Creggan Lower, Creggan Upper, Crosswood, Curragh, Curragh (Mechum), Derries, Friars Island, Garrankesh, Garrycastle, Garrynafela, Goldenisland (St. George), Goldenisland, Goldenisland (Kilmaine), Hillquarter, Kilmacuagh (Castlemaine), Kilmacuagh (Cooke), Kilmacuagh (Mechum), Kilnafaddoge, Kippinstown, Lissywollen, Loughanaskin, Loughandonning, Magheranerla, Meehan, Moydrum (West), Retreat, Srameen, Tullin, Tullycross and Warrensfields.

The neighbouring civil parishes are: Kilkenny West to the north, Ballyloughloe to the east, Kilcleagh to the south–east and St. Peter's (County Roscommon) to the west.

This article related to the geography of County Westmeath, Ireland is a stub.