Castletown Geoghegan is a village in County Westmeath, Ireland, and lies south west of Lough Ennell near the county town of Mullingar. It is around 13 km south-west of Mullingar and 19 km north of Tullamore. Castletown was the seat of the Geoghegan family of the medieval Barony of Moycashel in County Westmeath.