What defines a tragic hero?

According to Aristotle, there are some requirements of a hero for tragedy. His conception of a tragic hero finds expression in Poetics, especially in Chapter XIII of the book. He says that an ideal tragic hero should be good but not too good or perfect. The fall of a perfectly good man from happiness into misery would be odious and distasteful. His fall will not arouse pity as he is not like us. His fall would only shock and disgust us. Similarly, an utterly wicked person is not fit for the tragic hero. If such a man passes from happiness to misery, this may satisfy our moral sense. But he may want the proper tragic qualities. He is not also like us. His fall is felt to be well-deserved in accordance with the requirement of justice. It excites neither pity nor fear. Thus the perfectly good or the utterly wicked persons are not suitable to be the heroes of tragedies. In fact, they will be such persons whose misfortune is brought about not by vice and depravity but by some error or frailty. They must be highly renowned and prosperous.

Aristotle takes Oedipus Rex by Sophocles as a model for his concept of an ideal tragic hero. He has shown how King Oedipus can be regarded as a superb hero for a great tragedy. But his concept of an ideal tragic hero does not apply fully to Elizabethan or Modern tragedies. He is too rigid in his rules and principles. Modern literature has amply demonstrated it. Even plays Shakespeare has revealed new meanings in the ideas of the tragic hero. The tragic heroes created by him meet their catastrophe for some defect of character. The heroes in the tragedies of Arthur Miller and Eugene O'Neill are not people of higher rank. Rather they are very ordinary and common men. Yet they arouse feelings of pity and fear. The tragedy is also possible with saints as Shaw and Eliot have shown.