Beowulf is a classic hero of Anglo-Saxon literature. He appears when the king is most in need and saves the day by defeating the monster which is terrorizing the village. He is strong and honorable, and cares deeply for his countrymen who help him on his endeavors. Once he becomes king, he rules justly, and fights his last battle with the dragon, even though he is quite old – but he knows that he has to protect his kingdom.
On the other had, Grendel is a classic villain in the story. He is evil, but not inherently per se, but because he is a monster, and everybody is afraid of him although he hadn’t done anything bad in his “youth.” However, he turns evil once he becomes jealous of the people who have everything he will never be able to have. Thus he murders them, until a strong warrior like Beowulf comes, and makes him scared for the first time in his life, before killing the monster, of course.