A tragedy always requires a tragic hero. Macbeth himself fits the image of a tragic hero as he is valiant in battle and we have admiration for him even before he makes his entry on stage. He has killed the enemy, having fought the enemy against the odds. For this, his reward will be substantial.
He does however have a tragic flaw. If he did not, the play would end without drama. Macbeth indeed decides against murdering Duncan, as any noble host would do but his drive and ambition - and need to be a "man" in Lady Macbeth's eyes- get the better of him as
Evil waits patiently in the wings as Good takes her bow
Macbeth seems to think that it is not enough to wait for events to unfold and his fear of failure and unrelenting ambition drive him to commit acts that are against his better judgment and which he seems powerless to halt once he has started. His trust in the witches is misplaced and Lady Macbeth's ability to manipulate him also works against his weakening character. Whilst Macbeth is guilty of human pride and driving ambition - traits many audiences would relate to -
there is a certain doom implied in the witches' prophecies
that may make it seem as if he cannot fight cruel fate. Despite his noble birth and therefore seeming educated choices, Macbeth will make an error of judgment that will change his future. The futility of it all is not lost on Macbeth when, towards the end, and upon his wife's death, he becomes weary - but still intent:
"it is a tale
Told by an idiot
Full of sound and fury
A tragic hero does need to have an honorable end which has caused many discussions when referring to Macbeth. Honor in his day would be unrelenting purpose and so it would have been honorable, even against all the odds, to meet his end without surrender. Anything less would have been cowardly.
The fact that the many major characters are dead and that supernatural forces purposely
conspire against Macbeth and his kingdom
confirm this play as a tragedy. "Fair is foul and foul is fair" completes the paradox that is Macbeth. Macbeth is a victim of his own self and his understanding.