Arnulf de Montgomery (born c. 1066; died 1118/1122) was an Anglo-Norman magnate. He was a younger son of Roger de Montgomery and Mabel de Bellême. Arnulf's father was a leading magnate in Normandy and England, and played an active part in the Anglo-Norman invasion of Wales in the late eleventh century. Following the Montgomerys' successes against the Welsh, Arnulf established himself at Pembroke, where an earth and timber castle was erected, and was probably rewarded with the title Earl of Pembroke.