In Macbeth, Shakespeare introduces four main female character, Lady Macbeth and the three witches together. For each of them, he does not give a direct account of their qualities, but he lets their actions reveals their inner thoughts. The results is a round picture of evil characters.
First of all, Lady Macbeth is described as a deeply ambitious woman who lusts for power and position. For when the audience first see her, she is reading a letter from her husband telling her of the witches' prophecy she cannot bear even to mention the kingship directly; "thou ... shall be what thou shall art promised." But she is afraid he is not evil enough to obtain it by the most direct means. She reveals her own nature most fully in the address she then makes to the spirit of evil; "unsex me here, .... / And fill me .... / of direst cruelty."
Realizing that her husband's hopes of the crown may be impeded by his feeling of humanity, she prays that her own similar feelings may be suppressed. This proves that she is not the hard, cold, unfeeling villain of the play, but one who has to deal with these finer feelings of human beings to attain what she aim at. But she is, perhaps, more purposeful, less ready to consider secondary matters even those of conscience. This is why, unlike her husband, has no need of supernatural encouragement.
The theme of the relationship between gender and power is the key to Lady Macbeth's character. Her husband implies that she is a male soul inhabiting a female body. Thus, Shakespeare seems to use her and the witches to undercut Macbeth's idea that "undaunted mettle should compose / Nothing but males." These crafty women use female methods of achieving power to further their supposedly male ambitions. That is, women can be ambitious and cruel as men, yet social constraints deny them the means to pursue these ambitions on their own. Son, Lady Macbeth manipulates her husband with remarkable effectiveness, overriding all his objections. When he hesitates to murder, she repeatedly questions his manhood. Also, her strength of will persists through the murder of Duncan; it is she who steadies her husband's nerves immediately after the crime is perpetrated.
Afterwards, however, she begins a slow slide into madness. Just as ambition affect her more strongly than Macbeth before the crime, so does guilt plague her more strongly after it. By the close of the play, she has been reduced to sleepwalking through the castle, desperately trying to wash away an invisible bloodstain. Once the sense of guilt comes to her, her sensibility becomes a weakness, and she becomes unable to cope. Significantly, she dies, signaling her total inability to deal with the legacy of her crimes.
Similar to Lady Macbeth, the three witches plot mischief against Macbeth using prophecies. The witches are the instigators of the play because their prophecies prompt Macbeth to action. They are prompt him to murder Duncan, to order the deaths of Banquo and his son, and to blindly believe in his own immortality. The play leaves the witches' true identity unclear, but they clearly take a perverse delight using their knowledge of the future to toy with and destroy human being. In part, the mischief they cause stems from their supernatural powers, but mainly it is the result of their understanding of the weaknesses of their victims; for instance, they play upon Macbeth's ambition.
The witches are mainly called "the weird sisters", i.e. the sisters of fate, throughout the play. But even this title is insufficient, since they do not bring fate to Macbeth. Instead, they try to persuade him to do wrong or invite him to do it by deceiving him about what the future will hold. They embody evil and give to evil the respect which normal human beings give to goo; they chant together "Fair is foul, and foul is fair" at the end of the first scene.
To Banquo, who is less inclined than Macbeth in ignoable ambitions, they are content to prophecy, and their prophecies are favorable as his children are to be kings. To Macbeth, they represent the bad forces struggling for his soul. Knowing they are evil, he is free to make a chance. They win him by word-play, which is one form of deception. Later on, he demands to know what they are doing perhaps to know if their influence can be turned to good account. In reply, they bring up apparitions; the first warns him of Macduff; the second and third deceive him with hopeful prophecies which prove false. But he knows all the time that he is dealing with evil forces, for he tells his wife before his last visit to them; "I am bent to know, / But the worst means the worst." And he lives long enough to see how bad they are. When the second prophecy happens with Birnam wood appearing to move, he begins; "To doubt the equivocation of the friend, / That lies like truth." When Macduff says that he is not born of woman, Macbeth yarns; "be these juggling fiend no more believed."
Contrast to other female characters, Lady Macduff plays a small but much-loved part in the tragedy, since in the world of evils, she and her son represent confused and lovable simplicity. Her husband has left her, and she does not know why. Rosse tries to explain that Macduff has fled for his country's good, but Lady Macduff is unconvinced, and bitterly grieved; "All is the fear, and nothing is the love." Rosse himself does not seem to be really convinced, and is near to tear. He leaves and there is an exchange between Lady Macduff and her son in which the tragedy of the situation is heightened by what at first seems artful word-play on the subject of husbands and fathers, although this really a cover to feelings of tender love. The confusion reaches its height when Macbeth's agents murder Lady Macduff, although she has done no harm.
In conclusion, the audience cannot help noticing that women are sources of violence and evil. The witches' prophecies spark Macbeth's ambitions and then encourages his violent behavior; Lady Macbeth provides the brains and the will behind her husband's plotting. While the male character, Macbeth is just as violent and prone to evil as the women, the aggression of the female characters is more striking as it goes against prevailing expectations of men.