Ranulph or Ralph de Mortimer (before 1198 to before 6 August 1246) was the second son of Roger de Mortimer and Isabel de Ferrers of Wigmore Castle in Herefordshire. He succeeded his elder brother before 23 November 1227 and built Cefnllys and Knucklas castles in 1240.
In 1230, Ralph married Princess Gwladus, daughter of Llywelyn ab Iorwerth. They had the following children: