St Dwynwen's Church (Welsh: Eglwys Santes Dwynwen) is a ruined church on the island of Ynys Llanddwyn off the coast of the island of Anglesey, northwest Wales. Unusually for churches in that region it has a cruciform floorplan.
Coordinates: 53°08′16″N 4°24′47″W / 53.1377°N 4.413166°W