Tragic Irony
Similarly to dramatic irony, tragic irony requires an audience and so you see this type of irony exclusively in the realm of the performative--theatre, movies, books, etc. In this form of irony the words and actions of one character or more betray the real situation and tragic results ensue from those words and/or actions, about which the spectators are aware before the actors. The character speaking may realize the irony of his words while the rest of the actors may not; or he or she may be unconscious while the other actors share the knowledge with the spectators; or the audience may alone realize the irony. Probably the Greek play Oedipus The King by Sophocles is the play most wrought with tragic Irony. Oedipus becomes the king by unknowingly murdering his father and marrying his mother. So when Oedipus vows to comprehend and punish the man who murdered the former king, only the audience knows that he is vowing to punish himself. The tragic truths of the play's events are known only to the audience until the play's final conclusions. At that time it is revealed to Oedipus and the rest of the characters. As the Oedipus example so perfectly exemplifies, tragic irony is any circumstance in which dramatic irony is rampant and leads up to a final and tragic event or realization.