Oldcastle is a town in County Meath, Ireland. It is located in the north-west of the county near the border with Cavan, approximately 21 km from Kells. The R154 and R195 regional roads cross in the town's market square. As of the 2006 census the town's population stood at 2,226.
In recent years Oldcastle has grown mainly due to an influx of workers from Eastern Europe to work in the several industries, particularly furniture, bedding and victualling located in the area.