In Macbeth, the theme of good versus evil is central, depicted through the internal and external struggles of characters. Macbeth, initially portrayed as valiant and honorable, becomes consumed by ambition and the influence of the witches and Lady Macbeth, leading to his moral downfall. Despite the dominance of evil throughout the play, symbolized by the witches and Macbeth's tyrannical reign, good ultimately prevails with Malcolm's rightful ascension to the throne. Shakespeare suggests that while evil is potent, it does not triumph over good.

Evil in Macbeth is best illustrated by the actions of the three witches, Macbeth, Lady Macbeth, and the assassins hired by Macbeth. In contrast, good is depicted by King Duncan, Malcolm, Banquo, Macduff, Lady Macduff, and King Edward of England. Ironically, Macbeth, who becomes the epitome of evil, is initially depicted as good and honorable. An injured sergeant's report of him at the beginning of the play speaks of a courageous general:

For brave Macbeth--well he deserves that name--
Disdaining fortune, with his brandish'd steel,
Which smoked with bloody execution,
Like valour's minion carved out his passage...

Macbeth's ambition, spurred by the witches' predictions and Lady Macbeth's urging, turns him into a bloodthirsty tyrant. He and his wife plot the king's assassination and murder him in his sleep. This act sets him off on a journey of vile evil. Once crowned, he becomes paranoid and destroys anyone he deems a threat, including his best friend, Banquo, and Macduff's entire family.

Lady Macbeth initially appears more evil, urging her husband to carry through their plot. Her perfidy is illustrated in Act 1, scene 3:

I have given suck, and know
How tender 'tis to love the babe that milks me:
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out, had I so sworn as you
Have done to this.

Ultimately, she is destroyed by remorse, tortured by visions of their crime, and commits suicide. Macbeth, believing himself invincible due to the witches' predictions, meets his doom at the hands of Macduff, who was "from his mother's womb untimely ripped."

The witches take pleasure in Macbeth's ruin, using paradox and equivocation to confuse him. Their predictions empower him to commit further evils. The forces of good, led by Malcolm, Siward, and Macduff, eventually defeat Macbeth. His decapitated head is displayed, and Malcolm becomes the new king of Scotland, marking the triumph of good over evil.