Both Macbeth and Doctor Faustus are obsessed with gaining power. They are willing to commit terrible deeds in order to attain this power. Faustus is willing first to study the black art of magic and then to sell his soul to Lucifer in return for worldly power and "voluptuousness," and Macbeth commits murder in order to fulfill his ambition to become King of Scotland. Both are corrupted by the power they receive. Both men are also concerned with the supernatural. Macbeth has his ambition aroused by the prophecies of the witches, and Faustus by his meeting with Mephistopheles. Additionally, both men are able to delude themselves. Macbeth thinks he is impervious to defeat because of the witches' prophecy that only a man "not of woman born" can kill him, and then only when the forest marches on the castle. Faustus convinces himself that hell is a "fable" and an "old wives' tale," persuading himself that the sale of his soul will be without consequence.
Marlow’s character Doctor Faustus and Shakespeare’s Macbeth are famously flawed characters who fall victim to the vice of hubris. Hubris (excessive pride) is a staple of literary character weakness that stretches back to the ancient Greek playwrights, like Sophocles and his characters of Oedipus and Creon from his Theban trilogy.
Each character finds himself involved with the supernatural. Doctor Faustus makes a pact with the devil in order to secure earthly power. Macbeth witnesses the prophecies of the witches that lure him (and Lady Macbeth) into a plan to assassinate the king and take the throne for themselves. Both characters are unsatisfied with their lives and desirous of power, making them ripe for supernatural influences who then twist fate to their own ends.
Perhaps most poignantly, both characters realize the mistakes they have made and understand the depth of their own depravity.
After murdering several people, Macbeth says:
I am in blood
stepped so far that, should I wade no more,
Returning were as tedious as go o’er.
In other words, he feels that it is too late to turn back. He is already so guilty that he might as well continue on his bloody path.
Doctor Faustus, nearing the end of his life and facing an eternity in hell, says:
No Faustus, curse thy self, curse Lucifer,
That have deprived thee of the joys of heaven.
He knows that he is responsible, along with Lucifer, for his own damnation. Although he had numerous chances to change his mind and turn away from evil, he, like Macbeth, chose not to.