The many examples of irony in The Scarlet Letter by Nathaniel Hawthorne include that Hester is spurned by the local townspeople and made to wear the scarlet letter as a mark of her shame, yet she might be the one true character in the novel. She protects Dimmesdale, she atones to Chillingworth, and she maintains her her own code of ethics while raising Pearl alone.
With her husband distant, both physically and emotionally, Hester becomes lonely and eventually falls in love with the young Reverend Dimmesdale. When it becomes apparent that Hester is pregnant with no husband, she is marked a disgraced woman. The irony is that the townspeople and clergy look to Dimmesdale to chasten Hester, when he is complicit in her adultery. In fact, Chillingworth spots Hester in the public square and a local tells him Hester’s story, referring to Dimmesdale in reverent terms:
Mistress Hester Prynne, and her evil doings. She hath raised a great scandal, I promise you, in godly Master Dimmesdale's church.
Moreover, while Dimmesdale is too cowardly to admit his own wrongdoing until the end of the novel, Hester stands tall throughout the story. She remains true to her ethics in not revealing Dimmesdale’s name so as not to expose him to public shame. She also is honest with her husband, the cold and vengeful Chillingworth, in telling him, “I have greatly wronged thee,” but:
“Thou knowest,” said Hester,—for, depressed as she was, she could not endure this last quiet stab at the token of her shame,—“thou knowest that I was frank with thee. I felt no love, nor feigned any.”
It is clear that Chillingworth wronged Hester by marrying her, a much younger woman, even though she acknowledged that she had no feelings for him. Hester was very much imprisoned by the constraints of the society in which she lived.
Hawthorne uses irony with the theme of guilt and confession. Another clergyman tells Dimmesdale to get Hester to confess her sin and name her lover:
“Good Master Dimmesdale,” said he, “the responsibility of this woman's soul lies greatly with you. It behooves you, therefore, to exhort her to repentance, and to confession, as a proof and consequence thereof.”
The clergy, the townspeople, and also Chillingworth implore Hester to reveal his name. Chillingworth says:
“But, Hester, the man lives who has wronged us both! Who is he?”
“Ask me not!” replied Hester Prynne, looking firmly into his face. “That thou shalt never know!”
The irony is that Hester remains true to her morals by not confessing her lover’s name, while Dimmesdale betrays his morals by not confessing his sin. This irony is apparent when Dimmesdale, consumed with guilt and remorse, creates his own scarlet letter on his chest. This eventually leads to his death, although not due to the act of adultery, but due to his guilt over leaving Hester and his daughter Pearl to suffer alone.
The penultimate irony is that Chillingworth treats Pearl as if she were truly his daughter by bequeathing her his entire estate. This also leads to the final irony, which is that Pearl, although scorned as illegitimate, becomes “the richest heiress of her day, in the New World,” and therefore is completely accepted and “at a marriageable period of life, might have mingled her wild blood with the lineage of the devoutest Puritan among them all.” This final irony reveals the hypocrisy of the society at the time.