A dramatic irony is a literary device that is used to refer to a moment where something about a literary presentation has already been revealed to the audience but is unknown by characters in the presentation.
Dramatic irony is seen in Antigone where Creon, in the first scene, decrees that the body of Polyneices shall remain unburied and left in the open to rot, but the audience already knows that Antigone has already gone and buried him. The audience knows this because Antigone had said that she would rather face death by honoring her brother than allowing Creon’s decree to intimidate her.
Another example of dramatic irony can be seen when Creon is fuming that someone flouted his express decree, concluding that they must have been paid heavily for them to risk their lives in that way, but the audience already knows that it was Antigone who buried Polyneices’ body.