Into the Darkness
The evil side of Macbeth
Macbeth lets his greed get the best of him. When he murdered king Duncan, he feels rather guilty about it. He doesn't know how to cover up his actions very well. Then when Banquo poses a threat to his throne because his sons were prophesied to be kings and also he was there when the witches prophesied to Macbeth. So Macbeth orders murderers to go kill off Banquo and his son, Fleance. Macbeth ends up killing off several other families and acquaintances who may be a threat to his kingship.
The three witches
The witches represent evil in Macbeth because they are always stirring up evil. They enjoy tormenting people with evil. They prophesy to Macbeth that he will be thane of Cawdor, Glamis, and future king. This causes Macbeth to gradually change from good to evil.
At the start of the play, Macbeth is a valiant, good person. He is honorable in battle, and recognized for this. However, he is overcome by greed because he wants to be king. After he hears from the witches his prophesy of being king, and thanes of Cawdor and Glamis, he goes to whatever extent to make the prophesy true. Even at the expense of killing several people who stand in the way of his kingship.
Lady Macbeth's Character
Lady Macbeth appears to be evil from the start. Right when she receives the letter from Macbeth telling of the news from the witches, she instantly is in favor of murdering king Duncan. She doesn't even question the action and appears indifferent about the matter. She easily persuades Macbeth to be evil by telling him he needs to be more evil, and by murdering Duncan he would get what he desires.