Grendel, fictional character, a monstrous creature defeated by Beowulf in the Old English poem Beowulf (composed between 700 and 750 ce). Descended from the biblical Cain, Grendel is an outcast, doomed to wander the face of the earth. He revenges himself upon humans by terrorizing and occasionally devouring the warriors of the Danish king Hrothgar. Beowulf, a warrior and headman of the Geats (a Swedish tribe), engages him in combat and mortally wounds him. Grendel’s horrible mother avenges her son’s death but is also defeated and killed by Beowulf. Many critics have seen Grendel as the embodiment of the physical and moral evil of heathenism. Beowulf’s struggles to overcome the monster are thought to symbolize Anglo-Saxon England’s emerging Christianity. The 20th-century American writer John Gardner told the story of Beowulf from Grendel’s point of view in Grendel (1971).