Oldcastle may refer to:
Places Oldcastle, Bridgend, Wales, a ward Oldcastle, Cheshire, England, a parish Oldcastle, County Meath, Ireland, a town Oldcastle, Monmouthshire, Wales, a village Oldcastle, Ontario, Canada, an unincorporated community
People with the surname Sir John Oldcastle, a supporter of the Lollards in the 15th century Sir John Oldcastle, a play about him
Other uses Oldcastle Revolt, a revolt led by John Oldcastle
See also Old Castle (disambiguation)