Oedipus is the prototypical tragic hero, according to Aristotle in The Poetics. Aristotle has little to say about the play Antigone, which presents at least two primary tragic heroes: Creon and Antigone.
My favorite definition of tragic hero is critic Northrop Frye's:
Tragic heroes are so much the highest points in their human landscape that they seem the inevitable conductors of the power about them, great trees more likely to be struck by lightning than a clump of grass. Conductors may of course be instruments as well as victims of the divine lightning.
According to this definition, Creon, as king, is the "highest point" of the human landscape and the greatest "conductor" of divine lightning. Antigone is highest among women, ahead of her time in her outspokenness against men and authority. Therefore, Haemon and Eurydice are the lower points of the human landscape, the "clumps of grass," who are also struck down by the strike.
Death is also a deciding factor. Antigone dies; Creon suffers more. Haemon is affected by both Antigone and Creon's stubborness; Eurydice is affect by Creon's stubborness and the death of her son. It's a tragic cause and effect: hubris leads to bad law; hubris leads to stubborn rebellion of bad law; hubris leads to stubborn punishment of rebellion; hubris leads to hasty suicide.
Really, the play involves two lightning strikes, two tragic heroes who present two extreme cases of hubris in the exercise of and reaction to law and power. Sophocles, as much as he wants to be objective, sides with Antigone, I think. He gives her the moral high ground, as she upholds gods' law above man's.
The hero/heroine is Antigone herself and her tragic flaw is one of pride.
Antigone is too prideful and does not obey the law that King Creon has made for Theban citizens: that no one can bury Polyneices' body. Instead of listening to her ruler, Antigone decides to bury her brother anyway simply because she loves him. It is because of this pride that she is later condemned to death.
In the center of Sophocles' plays - Ajax, Antigone, King Oedipus, Electra, Philoctetes and Oedipus at Colonus - is the dramatic conflict of characters, who come to the awareness and knowledge of truth through their own suffering. As stated classical Bernard Knox, "Sophocles presents us, the first prototype of the tragic hero - a hero who helped by the gods and opposing the people make a decision knead until the level of his individual deep layer of his nature, physis, and then remains firmly in position in heroic manner, fierce, passionately even to self-destruction.
In Antigone, the play is centered on opportunity of the burial of traitor Polinice, Antigone's brother. Antigone's family loyalty enetrs into conflict with the responsibility and civic pride of King of Thebes, Creon. Finally, Antigone, one of the greatest literary figures, showing resistance to the authority, gets win, but with a terrible price. Creon finds the truth too late to save her and his family itself is destroyed.