This will take many of you back to college days: The complete text of A.C. Bradley on Shakespearean tragedy. [I read the book while an undergraduate and found that it brought a certain amount of order to the universe.] An excerpt:
In approaching our subject it will be best, without attempting to shorten the path by referring to famous theories of the drama, to start directly from the facts, and to collect from them gradually an idea of Shakespearean Tragedy. And first, to begin from the outside, such a tragedy brings before us a considerable number of persons (many more than the persons in a Greek play, unless the members of the Chorus are reckoned among them); but it is pre-eminently the story of one person, the 'hero,' 1 or at most of two, the 'hero' and 'heroine.' Moreover, it is only in the love tragedies, Romeo and Juliet and Antony and Cleopatra, that the heroine is as much the center of the action as the hero. The rest, including Macbeth, are single stars. So that, having noticed the peculiarity of these two dramas, we may henceforth, for the sake of brevity, ignore it, and may speak of the tragic story as being concerned primarily with one person.
The story, next, leads up to, and includes, the death of the hero. On the one hand (whatever may be true of tragedy elsewhere), no play at the end of which the hero remains alive is, in the full Shakespearean sense, a tragedy; and we no longer class Troilus and Cressida or Cymbeline as such, as did the editors of the Folio. On the other hand, the story depicts also the troubled part of the hero's life which precedes and leads up to his death; and an instantaneous death occurring by 'accident' in the midst of prosperity would not suffice for it. It is, in fact, essentially a tale of suffering and calamity conducting to death.
1 Julius Caesar is not an exception to this rule. Caesar, whose murder comes in the Third Act, is in a sense the dominating figure in the story, but Brutus is the 'hero.'