While describing the monstrous Grendel, the narrator alludes to the biblical figure of Cain:
Grendel this monster grim was called,
march-riever mighty, in moorland living,
in fen and fastness; fief of the giants
the hapless wight a while had kept
since the Creator his exile doomed.
On kin of Cain was the killing avenged
by sovran God for slaughtered Abel.
Ill fared his feud, and far was he driven,
for the slaughter's sake, from sight of men.
Of Cain awoke all that woful breed,
Etins and elves and evil-spirits,
as well as the giants that warred with God
weary while: but their wage was paid them!
“Exile doomed” by God, Grendel lives outside of human communities, in moors, marshes, and other wetland environments. The reason for his exile, the poem notes, is that Grendel is a descendant of Cain, the firstborn son of Adam and Eve who, in the Bible, kills his brother Abel out of jealousy. In the Bible, this is the first act of murder, and Cain is the first murderer. Accordingly, he is cursed to wander the earth, a curse which in some interpretations of the Bible extends to Cain’s descendants. In alluding to Cain here, then, the poem connects Grendel to a Biblical figure whose name is synonymous with murder, treachery, and jealousy. Additionally, the poem makes a more cryptic allusion to “the giants that warred with God,” which could be a reference to the Nephilim of the Bible or later Norse mythology.