One can compare Grendel from the story about Beowulf with Goliath from David and Goliath in the Bible. Just as Grendel is against Beowulf, it is Goliath against David.
Grendel appears to be this monster that no one can beat, like Goliath does in the story of David and Goliath. Grendel is described as a vaguely human in shape, though much larger "... The Other, Warped into the shape of a man, moves beyond the pale Bigger Than any man, An Unnatural birth called Grendel by the country people into shapes days." (Pg. 95 lines 1351-1355), he has put fear into the people and no one seems to have the strength or courage to fight him "Grendel's hatred began, ... the monster relished his savage war. On the Danes,