Castlerea is a town in County Roscommon, Ireland. It is located in the west of the county and had a population of 2,348 at the 2022 census. Roughly translated from Irish, Castlerea is generally thought to mean 'brindled castle'. An alternative translation is 'castle of the king'. The town is built on the banks of the River Suck and the River Francis, both of which are tributaries of the River Shannon.