In Poetics, Aristotle cites many ancient Greek plays, but Sophocles's Oedipus the King is the one he mentions most frequently as an example of a well-constructed tragedy with a dramatically effective protagonist.  In fact, Aristotle's model of tragedy seems closely based on his admiration for this particular play.  Here, he uses the play's protagonist as an example of effective characterization:

                        p. 21: So it is clear first of all that decent men should not be seen undergoing a change from
                        good fortune to bad fortune—this does not evoke fear or pity, but disgust…Nor again should
                        a very wicked person fall from good fortune to bad fortune—that kind of structure would be agreeable,
                        but would not excite pity or fear, since the one has to do with someone who is suffering undeservedly,
                        the other with someone who is like ourselves (I mean, pity has to do with the undeserving sufferer, fear
                        with the person like us); so what happens will evoke neither pity nor fear….We are left with the sort of person                                         intermediate between these.  This is the sort of person who is not outstanding in moral excellence or justice;
                       on the other hand, the change to bad fortune which he undergoes is not due to any moral defect or depravity,
                       but to an error [hamartia] of some kind.  He is one of those people who are held in great esteem and enjoy
                       great good fortune, like Oedipus (21).