The Château de Regnéville is a ruined 14th century castle in the commune of Regnéville-sur-Mer in the Manche département of France. Built at the edge of the Sienne river estuary, it was intended to protect the important dry harbour of Regnéville-sur-Mer, one of most active of the Cotentin Peninsula from the Middle Ages until the 17th century. Partly dismantled at the end of the Hundred Years' War, it was much altered during the 17th and 18th centuries. Today it is the property of the département.