Macbeth is a tragic hero who is undone by his own ambition and secret desire to become king. This is the tragic flaw, or hamartia, that results in his final doom. The irony of this tragic flaw is that Macbeth recognises himself the impact that his ambition is having upon him and almost predicts how it could all end badly in his soliloquy in Act I scene 7:
I have no spur
To prick the sides of my intent, but only
Vaulting ambition which o'erleaps itself
And falls on th'other.
Macbeth is a character that not only has his tragic flaw but also allows himself, at least initially, to be dominated and influenced by his wife. This is one area in which perhaps Macbeth as a tragic hero is distinct, as in other cases, such as Julius Caesar, he ignores his wife's advice.
If Macbeth's tragic flaw is his ambition, in other tragic heroes the hamartia is different. In King Lear, for example, Lear is undone by his own strong pride that causes him to mistake his two unfaithful daughters to be faithful and to identify the one daughter that loves him truly as being ungrateful. Cordelia's response in honestly only giving her father the love that it is her duty to give backfires disastrously, even though she retains her integrity, as Lear ends up disowning her:
Here I disclaim all my parental care,
Propinquity, and property of blood,
And as a stranger to my heart and me
Hold thee from this forever.
Lear's tragedy is made in the foolish decision that his pride drives him to in Act I scene 1, and he is distinct from the tragic hero of Macbeth in the nature of his tragic flaw and in the fact that throughout the play he is only surrounded by characters who love him, support him and want what is best for him. This is of course in sharp contrast to Lady Macbeth.