Castletown

Castletown may refer to:
 * Castle town, a settlement built adjacent to or surrounding a castle

Australia

 * Castletown, Western Australia, a suburb of the remote town of Esperance

Republic of Ireland

 * Castletownroche, County Cork
 * Castletown, County Cork (disambiguation), several townlands and villages
 * Castletown, County Laois
 * Castletown, County Limerick, a townland and village in County Limerick
 * Castletown House, County Kildare
 * Castletownbere, County Cork
 * Castletown-Geoghegan, County Westmeath
 * Castletown, County Wexford
 * Castletown Kilpatrick, County Meath

Isle of Man

 * Castletown, Isle of Man

United Kingdom

 * Castletown, Cheshire
 * Castletown, Dorset
 * Castletown, Highland, Scotland
 * Castletown, Penrith, Cumbria
 * Castletown, County Antrim, a townland in Islandmagee, County Antrim, Northern Ireland
 * Castletown, County Tyrone, a townland in Carnteel parish, County Tyrone, Northern Ireland
 * Castletown, Sunderland
 * RAF Castletown, Scotland

Other uses

 * Castletown (horse), a New Zealand Thoroughbred racehorse
 * Castletown, County Mayo, the fictional setting of the mockumentary Hardy Bucks