It is never directly stated in the poem whether Grendel is man or a monster such as a troll or a demon; the story does however relate that Grendel is a descendant of the biblical Cain, the first murderer. If Grendel is indeed a man, he is also a cannibal since he kills men and eats them. Grendel, however, is invulnerable to human weapons, so from this we can at least adduce that he is not entirely human.
