Cosmic irony is simply the irony of fate, and if there's one thing that Oedipus Rex is about, it's fate.

Oedipus's downfall is directly related to his inability to comprehend the role of fate in mortals's lives and how it is manipulated by the gods for their own ends. Oedipus acts as if he can defy fate, even after he's been explicitly warned of the consequences of his actions by the blind seer, Tiresias. Of course, he can't outsmart fate, and the end result of his stubborn defiance is the exact opposite of what he'd expected; this is what makes it ironic. Every step that Oedipus takes to try to avoid his fate—such as attempting to get to the bottom of how his father was killed—only brings him nearer to his eventual doom.

Cosmic irony is a phrase that is best described by considering the presentation of the gods in a text and how they act in relation to humans. Cosmic irony normally refers to gods who are at best profoundly indifferent but at worst actively antagonistic towards the humans that populate the earth. Cosmic irony can be seen therefore in the way that Oedipus ends up King of Thebes, which is actually his former city where he was born, even though he knows nothing of this, and that although he saved Thebes through solving the riddle of the sphinx, he is actually the cause of a far larger calamity because of his identity and the plague and suffering that this brings upon his city.

In the end, the fate of Oedipus is shown to have nothing to do with his own personal character: there was nothing, after all, that he could do to avoid it. The fate of Oedipus is an example of cosmic irony because it depicts the gods to be cruel and callous individuals who use humans as playthings, as the Chorus suggests in the following speech which comes just after Oedipus enters the stage having blinded himself:

What god,

What dark power lept beyond all bounds,

beyond belief, to crush your wretched life?

Cosmic irony is therefore shown in the way that Oedipus has no idea whatsoever at the beginning of the play of who he really is and how this will blight his existence. His fate is unavoidable, and it seems indeed as if the gods have deliberately "lept beyond all bounds, / beyond belief" to "crush" the "wretched life" of Oedipus.

What is an example of dramatic irony in Oedipus Rex?

Dramatic irony is where the audience knows something that the characters in the play don't. In Oedipus Rex, Oedipus is determined to find the killer of King Laius, whose widow Jocasta he has married. A terrible plague has descended upon the city, and the only way to lift this curse is by finding the man who killed Laius. As Oedipus takes his duty as king seriously, he sets out to do precisely this, for the good of his family and for his people.

The irony here of course is that it was Oedipus himself who—unwittingly—killed Laius after an argument by the side of a road. We know, but Oedipus does not, that Laius was his real father, the man who abandoned him as a baby to avoid the consequences of a particularly ominous prophecy. So when Oedipus vows to his people to find the killer of King Laius, he is setting himself on a dangerous course of self-discovery, one that will reveal his identity as the murderer.

What is an example of dramatic irony in Oedipus Rex?

We, the reader/audience, also know way before Oedipus does that he has in fact killed his father and married his mother. Since the time of the prophecy, Oedipus has gone to great pains to avoid the fruition of the fortune telling.  We know well before Oedipus does that he has run right into the prophecy's fullfillment.  The hints are all over the play...speeches, and the chorus' responses.

What instances of dramatic irony appear in Oedipus Rex?  

Well, the whole play is structured around what, to its original audience, would be one colossal case of dramatic irony. Sophocles' audience would have already known the Oedipus story, and the very name "Oedipus" would be synonymous with sleeping with his mother and killing his father. That means that, even before the play began, the audience would know the ending. This terrific dramatic irony would mean that, every time Oedipus talks about finding the cause of the Theban plague, the audience would know exactyl what the cause was: Oedipus himself.

Within the construction of the play, there are ironies all over the place. As Oedipus killed his father on the crossroads, he felt confident that he'd left his father behind him in Corinth. Oedipus solves the riddle of the Sphinx (focussing on the way that time ages and weakens men) but the crown of Thebes which he wins causes him to become aged and weakened in just the same way.

Oedipus is determined to find out the truth, and seek the murderer so that he can see him and confront him. Of course, Oedipus does find the truth and the murderer - but he can't see him - because he is Oedipus. Oedipus' response is to blind himself.

Even Oedipus' name is an irony: it means "swollen-footed" or "I think I know", meaning that both Oedipus' origins as the Theban heir and his self-assured insistence on knowing are written tragically into his very name from the first moment of the play.

There are many more to find! Hope it helps!

What is an example of irony in Oedipus Rex?

A particularly good example of irony comes when Tiresias, the blind prophet, confronts Oedipus and accuses him of being the one who killed King Laius. Oedipus is outraged at such a suggestion and refuses to listen to Tiresias. If he really is guilty of such a heinous crime, then it also means that the woman who is his wife, Jocasta, is also his mother. And that's just too horrible for him to contemplate.

The irony here is that Tiresias, though blind, has the gift of foresight. This was given to him by the goddess Athena as compensation after she took away his sight. (Athena made Tiresias blind after he accidentally saw her bathing one day.) Despite his disability, however, Tiresias' extraordinary powers of foresight make him a wise and respected seer, someone whose unique abilities to divine the will of the gods mean that his prophecies must always be respected.

Yet, in a further irony, it is Oedipus who is figuratively blind in this particular scene. And it is his blindness, his stubborn refusal to pay heed to Tiresias' prophecy, that will ultimately lead to his downfall and his own, literal blindness. When Oedipus finally comes to grief, he gouges out his own eyes. But, unlike Tiresias, his blindness is not compensated with the gift of foresight.

What is an example of irony in Oedipus Rex?

As the other answers have noted, Oedipus Rex is filled with dramatic irony in the sense that the audience comes into the playing knowing what Oedipus does not. Situational irony can be recognized in the play as well. Situational irony occurs when the facts of a situation work out to be completely different from what the characters expect.

Oedipus, for example, is a very proud man, and it never once occurs to him that his sin could be the cause of the plague in Thebes. When he calls for a harsh sentence to fall on the head on the person responsible for the plague, the irony is that he doesn't know that the person he is condemning is himself.

Another instance of situational irony occurs as follows. Ironically, when he hears the prophecy that he will kill his father and marry his mother, Oedipus flees Corinth to escape this horrible fate. What he doesn't realize is that the parents he flees from are not his real parents. The irony is that he runs directly towards his real parents in attempting to run away from them, and, therefore, unwittingly kills his father and marries his mother. This is the exact opposite of what he intended to do. But the point of the play is that one's fate can't be avoided.

What is an example of irony in Oedipus Rex?

Dramatic irony occurs in the story because the audience is aware that it is Oedipus that killed Laius, but Oedipus is unaware and demands that the murderer is found and punished.

The audience is also aware that Oedipus was adopted by Polybus and Merope. However, Oedipus unknowingly runs from his adoptive parents, believing that he is forestalling the outcome of the prophecy that he would kill his father. He later discovers that the man he murdered on the road was indeed his father and that his biological parents are Laius and Jocasta.

Oedipus mocks Teiresias’s blindness not knowing that the situation is quite the opposite. Although Teiresias is blind, he is aware of what Oedipus has done, but Oedipus himself has no clue of the impending disaster due to his actions. In the end, Oedipus turns blind after he damages his eyesight.

The audience is aware that Oedipus is the cause of the plague because he married his mother. Oedipus discovers the incestuous relationship much later in the story.

What is an example of irony in Oedipus Rex?

Irony is, in fact, a literary technique which originated in Greek tragedy. Most common is dramatic irony in which a character's actions or words are understood by the audience, but unknown to the character.

The drama of Oedipus Rex is based upon the psychological blindness of Oedipus who issues punishments for the murderer of King Laius, who ruled Thebes before King Oedipus. For, he is unknowingly that very murderer who is the cause of the suffering of the people in Thebes.

So, in SCENE I when Oedipus says,

I pray that that man's [the killer of King Laius] life be consumed in evil and wretchedness (234)

Oedipus ironically curses himself. This is an example of dramatic irony, because Oedipus at this point in the drama is unaware of his own guilt and what will become of him.

In another example of dramatic irony from SCENE III, a messenger arrives to inform Oedipus that Polybus "was not your father." For, a shepherd had given the baby Oedipus to this messenger, who in turn gave Oedipus to Polybus. Nevertheless, Oedipus fearlessly replies with great dramatic irony,

But I
Am a child of Luck; I can not be dishonored.
Luck is my mother; the passing month, my brother,
Have seen me rich and poor. (1022-1026)

Of course, Oedipus is, indeed, greatly dishonored and cursed with his own words. And, because he was blind to the truth, he physically blinds and banishes himself.

What is the dramatic irony in the play Oedipus Rex, by Sophocles?

The dramatic irony in the play Oedipus Rex, by Sophocles, is that through the soothsayer Teiresias, the audience becomes more aware and more convinced that Oedipus is the murderer of the late King Laius; not only that, Laius is actually Oedipus’s father, Oedipus has married his mother, and all of Oedipus’s children have been born from incest.  Teirsias flat out tells Oedipus and the audience that Oedipus is the murderer of Laius when he says “I say that thou art the murderer of the man whose murderer thou pursuest.”  It takes Teirsias a lot longer to tell Oedipus that his problems run much deeper than just murder, but by the time Teirsias has left the scene the audience has learned that Laius was Oedipus’s father, that he has married his mother, and procreated children that are both his children and his siblings.  Teirsias first illudes to Oedipus’s lineage when he says “I say thou livest with thy nearest kin in infamy, unwitting in thy shame,” and again later when he says, “thou hast eyes, yet see’s not in what misery thou art fallen, nor where thou dwellest nor with whom for mate.  Dost know thy lineage?”  Finally, the audience becomes convinced of Oedipus’s plite when in Teirsias’s final speech, Teirsias describes Laius’s murderer as wearing purple robes and leaning on a sceptor, that the murderer will be proved to be both brother and sire to the children in his home, and that their mother will prove to have born both a son and husband to herself and a murderer to his sire.  All of which, Oedipus completely disbelieves until he relentlessly examins the evidence throughout the rest of the play.

What are some examples of Sophocles’s use of dramatic irony in his play Oedipus Rex?  

Dramatic irony arises from a circumstance in which an audience member knows something about a character or situation in a play that a character doesn't know.

A person unfamiliar with the ancient Greek Oedipus myth as dramatized in Sophocles's Oedipus Rex would experience far fewer examples of dramatic irony in the play than a person who is already familiar with the myths surrounding Oedipus.

An audience member watching a performance of Oedipus Rex at the Festival of Dionysus in 429 BC was already familiar with the Oedipus myth. They heard the myth repeated time and time again from a young age, and they knew the myth of Oedipus and the characters involved in the story as well as a modern audience member knows any fairy tale or superhero adventure story.

The playgoer in 429 BC knew before the play begins that Oedipus killed his father, Laius, and married his mother, Jocasta. They knew that Oedipus saved Thebes from the Sphinx. They knew the names of Oedipus and Jocasta's four children. They may have even known what Oedipus had for breakfast on the fateful day in Sophocles's play that Oedipus discovers that he did, in fact, kill his father and marry his mother.

An audience member attending Oedipus Rex in 429 BC wasn't interested in the story, which they already knew. They would have wanted to know how the playwright crafts the story, the changes and twists and turns, if any, that the playwright adds to the story, and the playwright's skill as a poet.

In Poetics, Aristotle praises Oedipus Rex as a perfect example of a Greek tragedy and cites Oedipus as a perfect example of a tragic hero. Aristotle refers to only one event in the play—when the messenger comes to Thebes to tell Oedipus that his adoptive father, Polybus, has died—and assumes that his reader knows the rest of the story.

For the audience member familiar with the Oedipus myth, almost the entirely of the play was an example of dramatic irony. They already knew what's going to happen. What they wanted to know was how the playwright made it happen.

For an audience member unfamiliar with the Oedipus myth, Oedipus Rex is a murder mystery: who killed Laius? The viewer watches the plot of the story unfold and picks up clues to the murder along the way. There's very little dramatic irony because the viewer has no idea what's going to happen.

In time, the viewer learns, along with Oedipus, that Oedipus killed Laius, just like Teiresias said he did. They also learn the whole backstory about Oedipus being fated by the gods to kill his father and marry his mother, how as a newborn baby Oedipus was taken to the mountains to die, how Oedipus came to be adopted by King Polybus and Queen Merope in Corinth, how Oedipus saved Thebes from the Sphynx, and all of the many other elements of the Oedipus myth that Sophocles managed to integrated seamlessly into Oedipus Rex.

Accordingly, in exploring and discussing elements of dramatic irony in Oedipus Rex or any other play based on well-known myths and legends, it's important to consider the point of view of the audience member and clearly distinguish between foreknowledge and hindsight.

What are some examples of Sophocles’s use of dramatic irony in his play Oedipus Rex?  

The other answer does an excellent job of listing specific examples, but it's also important to note the factor that unites them: the person who does not know the truth of the situation is almost always Oedipus. His metaphorical blindness to reality leads to his literal self-blinding at the end of the play.

In many plays, dramatic irony involves the audience knowing something that none of the characters do. However, in this play, one of the foundational texts of the tragic genre, other characters—Tiresias, the shepherd, etc.—have some crucial knowledge that Oedipus does not. In a way, Tiresias represents the audience, in that he has the painful knowledge that they also possess; the difference is that he, unlike the audience, is able to tell Oedipus the whole truth if he wants to. So, rather than being generalized to the whole cast of characters, the dramatic irony targets Oedipus specifically.

What are some examples of Sophocles’s use of dramatic irony in his play Oedipus Rex?  

“Dramatic irony” has been briefly and helpfully defined at dictionary.com as follows:

irony that is inherent in speeches or a situation of a drama and is understood by the audience but not grasped by the characters in the play.

Sophocles’ tragedy Oedipus Rex displays numerous examples of dramatic irony, including the following:

• At one point Oedipus declares that the man who killed Laius may also kill Oedipus (167-69; Ian Johnston translation; see link below). He does not know, of course, that he is the man who killed Laius, although anyone familiar with the Oedipus legend would know this.
• Oedipus ironically proclaims that by avenging Laius he will serve himself (170).
• Oedipus vows to discover the criminal lest a “common ruin” afflict Thebes (177). Of course, by discovering the criminal (himself) he ruins his own life.
• At one point Oedipus declares,

If someone knows the killer is a stranger,

from some other state, let him not stay mute. (268-69)

Oedipus, of course, was originally not from Thebes.

• Oedipus declares that the killer of Laius is the cause of the city’s “pollution” (281), not realizing, of course, that he is the killer of Laius.
• Oedipus hopes that the killer of Laius will suffer “the worst of agonies” (287) – a fate, of course, that will eventually be his own.
• Oedipus says,

. . . I pray, too,
that, if he should become an honoured guest
in my own home and with my knowledge,                                
I may suffer all those things I’ve just called down
upon the killers. (288-92)

The dramatic irony of this prayer should be obvious.

• Oedipus notes that he is now married to Laius’s wife, not realizing, of course, that this woman is his own mother (303).
• Oedipus laments that “fate swooped down” on Laius’s head (308), not realizing that fate is about to swoop down on his own head.
• When Tiresias will not tell Oedipus what Tiresias knows about the killing, Oedipus calls him the “most disgraceful of disgraceful men!” (399) – a description that will later fit Oedipus himself especially well.
• Oedipus accuses Tiresias of having had some role in Laius’s death – an ironic accusation if there ever was one (412-17).
• Tiresias tells Oedipus that someday the latter’s eyes will be dark (505-06), but there is no way at this point for Oedipus to realize that he will later blind himself.
• Tiresias reveals many specific details about the killer’s identity (546-59), but Oedipus cannot see (as the audience can) how these details are relevant to his own life.
• Oedipus accuses Creon of having killed Laius (640), not realizing that he himself is the killer.

As should be obvious by now, the specific dramatic ironies that exist in Oedipus Rex are almost too numerous to list, making it one of the most ironic plays ever written. Anyone who reads the play for a second time or who knows the Oedipus legend before reading it cannot help but be struck by the tremendous number of particular dramatic ironies the play reveals.

When does dramatic irony happen to Oedipus in Oedipus Rex?

I think that dramatic irony happens at several points in the play.  When Tiresias' words of "How terrible is wisdom when it brings no profit to the wise" are spoken, and the reader sees Oedipus' dismissive actions and demeanor towards such a warning, it is a moment of dramatic irony.  The reader understands that there is a loaded meaning, a specific connotation in the words, but the character (Oedipus) does not.  The same experience can be seen in the articulation of Oedipus' fate that he will kill his father and marry his mother.  The reader is convinced or fully grasps something that the character (Again, Oedipus) does not.