Castletown is a small village and also a parish in County Laois in Ireland. The older Irish name for the town was Baile Chaisleáin Ua bhFoirchealláin. This has been anglicised as Ballycashlan-Offerillan and Ballycaslane-Offeralane. Uí Fhoirchealláin is the name of the parish and was added to distinguish it from another Castletown.