As nobody knows the name of the person who wrote Beowulf, literary scholars call this individual the Beowulf poet. The poem was written between 975 and 1025, making it one of the oldest extant works of British (in this case, Anglo-Saxon) literature. Important characters include Beowulf, Hrothgar, Unferth, Grendel, Grendel's mother, the dragon, and Wiglaf.
Many of the knightly men in Beowulf, especially Beowulf, represent the highest values in Anglo-Saxon culture. These men also include Hrothgar, lord of the mead hall, and the knight Unferth. Unferth is wrong to challenge Beowulf's claims to having bested Brecca, but he reveals a deep knowledge of the honor code that the men live by. In contrast, Grendel, who is associated with the Biblical Cain, a murderer, represents the chaos and self-centered spitefulness that uses power destructively and selfishly. He is without honor.
Beowulf is characterized by his great physical strength, courage, and loyalty. As a loyal member of his society, Beowulf uses his physical gifts for the good of the community, putting the needs of the whole ahead of his personal desires.
It is this loyalty to community that leads Beowulf to travel with his men to Heorot, the famous mead hall terrorized by Grendel. Heorot symbolizes all that is best in human community: loyalty to one's lord and comrades, warmth, safety, food, culture, companionship, and order. These attributes of civilization are threatened by the intrusion of the monster Grendel and, later, his mother.
Grendel has been terrorizing the mead hall for twelve years. He is driven by a deep resentment of humans and their capacity for building civilization: not only does he want to feed on human flesh, he wants to destroy the joy of the human community. He is able to do so because of his superior strength. He represents the negation of the good the mead hall embodies.
Beowulf puts an end to Grendel's terror. He studies Grendel and realizes that with his own enormous arm strength, he can grab Grendel's claw and rip out his arm. He does so, killing the creature and saving Heorot.