Castle Saunderson is a castle near Belturbet in County Cavan, Ireland. It was the former family seat of the Saunderson family, and is now in ruins. The Finn River flows along the north-eastern edge of the Castle Saunderson Demesne, where the river enters a narrow channel of Upper Lough Erne. The castle is about a half a mile west from Wattlebridge, a small hamlet in the south-south-east of County Fermanagh.