Beowulf is an epic poem depicting an epic hero, Beowulf. The poem depicts the values and virtues not only traditional in epic poetry, but specific to historic Anglo-Saxon values.
Four virtues celebrated by Anglo-Saxons and revealed in Beowulf include loyalty, generosity, brotherly love, and heroism.
Beowulf is loyal to Hrothgar and seeks to help his kingdom despite the fact that he is not a Dane, because the king once helped Beowulf's own father. Beowulf's loyalty extends beyond repaying a family debt however. He returns to his homeland of Geatland after defeating Grendel and Grendel's mother, and pays honor to his own king. He also proves it again and again to his own men, even up until the point he fights the dragon.
Beowulf also displays generosity. Most obviously, as expected, he brings the gifts bestowed upon him from the Danes back to his own uncle and king of Geatland. But it could also be argued that part of Beowulf's motivation to help the Hrothgar in the first place stems from a heart of generosity.
Brotherly love is seen most prominently in Beowulf's relationship with his men. Rather than assuming a position of honor after the defeat of Grendel, he chooses to sleep with his men in the Great Hall. Though he is clearly the man of honor, he never turns his back on these men, and they never turn their backs on him. His continued relationship with Wiglaf, his right hand man, at the end of his life, is a final piece of evidence that Beowulf displayed brotherly love.
Finally, Beowulf is a traditional hero. He is courageous in the way he is unafraid to fight Grendel, go after Grendel's mother, and finally take on the dragon, even as an old man. He has brute physical strength, evidenced by his grip on Grendel's arm and the amount of time he can both hold his breath and fight Grendel's mother under water. And of course, he displays both skill and resourcefulness in battle, which is evidenced by all of his success.