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Piggy and Lady Macbeth share very few similarities, but a few comparisons can be drawn:
1. Both are characters in works of fiction that focus on themes of the corruption and evil of man.
2. Both Piggy and Lady Macbeth act like 'sidekicks' or supporting characters to the main characters in the story. The difference here is that while Piggy encourages Ralph toward goodness, Lady Macbeth encourages her husband toward murder so he can usurp the throne of Scotland.
3. Both Lady Macbeth and Piggy die before the end of the story, forcing the main characters to face the final climax alone.