Edward de Villefort
Poor little Edward gets the short end of the stick. His father doesn't love him. His mother does love him, but she can only express it by poisoning other people. He's so strange and creepy that he, young though he is, is a suspect in the poisoning case. Oh, yeah, and then he gets poisoned by his mother.
What's the moral of the story? In the grand scheme of things, Edward is the straw that broke the camel's back, the first unintended casualty in the Count's war on the men who betrayed him. If the Count had been able to revive Edward with his healing tonic – but he wasn't, so there's no point in discussing it. As Dumas tells us, after the incident the Count is left "wondering for the first time whether he had the right to do what he had done" (91.100). Without Edward's death, that moment of clarity may never have come.