Mortemer Abbey (French: L'Abbaye de Mortemer, pronounced [labei də mɔʁtəmɛʁ]) is a former Cistercian monastery in the Forest of Lyons between the present Lyons-la-Forêt and Lisors, some 34 km (21 mi) southeast of Rouen in the department of Eure. It is located on the territory of the commune of Lisors.