Poetic justice is defined as a character getting a fitting fate based on their actions. Poetic justice is therefore seen as a character getting what they deserve or receiving their deserved comeuppance. For Macbeth, poetic justice is seen in his end because it comes through trusting in the same prophecies that he trusted in at the beginning of the play that predicted his rise to the position of King of Scotland. Note how Macbeth himself recognises this in Act V when Macduff tells him that he is not "of woman borne":

I will not yield,
To kiss the ground before young Malcolm's feet,
And to be baited with the rabble's curse.
Though Birnam wood be come to Dunsinane,
And thou opposed, being of no woman born,
Yet I will try the last.

Macbeth thus dies as a result of trusting in the same prophecies that he trusted in initially to spur him on to kill Duncan. In the same way, poetic justice is seen in the character of Willy Loman. He spends his entire life avoiding the fact that he is a failure and eventually can only ultimately avoid this by killing himself. For the characters in Lord of the Flies, it is harder to see how they receive poetic justice. Piggy and Simon are killed, but they are portrayed as innocents who are the victims of the natural evil within humans rather than bad characters who get what they deserve.