Which characters in Macbeth would you say are more like Beowulf, and which would you say are more like the monsters?
In comparing Shakespeare's Macbeth, and the epic, heroic poem, Beowulf, there are heroes and monsters in both.
In terms of heroes, Banquo is like Beowulf. He values his honor above personal gain, supporting Duncan with each breath, on the battle field and off. Banquo pays little attention to the witches prophecies for him: even when they tell him that he will father a line of kings. In Act I, Duncan promises to reward Banquo for his accomplishments on the battlefield; but the soldier responds that when Duncan prospers, Banquo prospers, and that is reward enough.
Macduff can also be considered a hero like Beowulf. He, also, is fiercely loyal to the King. And like Beowulf, he takes on his most powerful adversary without thinking twice about it.
In terms of the monsters in Macbeth, Lady Macbeth is monstrous in her own right: she tells her husband that she has the wherewithal to murder her child while nursing it, if she had promised her husband that she would do so. However, it does not take long before guilt overpowers her, she starts to lose her mind, and ultimately she takes her own life.
On the other hand, Macbeth may start out hesitant about killing Duncan, and guilt-ridden after he does so, but after a while, murder becomes much easier for him. Whereas Lady Macbeth begins to falter in their plans to hold onto the throne, Macbeth becomes more determined and more viscous. By the end of the play, he has alienated himself from everyone; even the malcontents and mercenaries who have fought for him start to join the other side and fight against him. Everyone fears him, and he seems almost insane when he murders Banquo, and then Macduff's entire family.
Macbeth is certainly the character who most closely resembles a monster.
Beowulf is a hero who showed his loyalty and sense of duty in going to help Hrothgar and his people as they helped Beowulf's father. He is strong, fearless, and loyal to family.
I would venture to say that Macduff and Banquo are closest to Bewulf. Both Macduff and Banquo are strong and fearless--both are given many honors and accolades for their performances on the battlefield. Banquo sacrifices himself for his son, Fleance; therefore, he is loyal to family. Macduff, even though he fled to England for the good of Scotland, has abandoned his family and left the vulnerable to Macbeth's machinations. This is where Macduff has fault, although it could be argued that he had the bigger picture in mind and was fighting for a safe and peaceful Scotland so his family would enjoy greater solace.
The witches are like the monsters, as they enjoy toying with people and their lives. Macbeth is also monster-esque in his character development. He is blood-thirsty and destroys anyone who stands in his way of success. One could argue, too, that Macdonwald is like the monsters in Beowulf, except that we only have the few statements of those who opposed him in battle as proof.