"A tragic hero in literature is a protagonist that is otherwise perfect except for a tragic flaw, also known as fatal flaw, that eventually brings him down in the end. The concept of the tragic hero was created in ancient Greek tragedy and defined by Aristotle. In fact, an Aristotelian tragic hero must have four characteristics: goodness, superiority (this can be in terms of politics, reputation, etc), a tragic flaw that eventually leads to his demise, and a realization of both his flaw and his demise."

Relating this to Othello, he is definitely the protagonist of the play. it is even named after him. His tragic flaw - low self confidence, pride and a barbaric nature, causes his demise at the end of the play, with the murder of his wife and then his suicide. Othello is a tragic hero...