William Shakespeare, Hamlet

The elder Hamlet's ghost tells Hamlet to seek revenge for his murder; Hamlet frets; he kills Polonius by accident; he indirectly causes Ophelia's death; he has Rosencrantz and Guildenstern killed; he kills Laertes and Claudius in a fencing match and inadvertently kills Gertrude by not drinking the poisoned wine intended for him; he is in turn killed by Laertes.