The play's "tragic" hero, Sir Robert Chiltern is an accomplished government official, considered by all as an ideal husband and model politician. As described in the stage notes, Sir Robert has effected a violent separation of thought and emotion in his personality; moreover, he suffers from divided loyalties. Though a portrait of distinction and good breeding, Sir Robert conceals a blemished past. Extremely ambitious, he succumbed to the nefarious advice of his mentor, Baron Arnheim, in his youth, coming to hold power over others as life's primary pleasure and wealth as the age's weapon toward winning it. To some extent, Sir Robert holds wealth and power in similar esteem today. At the same time, Sir Robert has had to conceal his past from his wife in hopes of keeping her love. As detailed below, Lady Chiltern's love is predicated on the worship of his perfect image; so desperate is Sir Robert to remain in her esteem that he will even agree to resign from government in Act IV. Torn between his true and ideal selves, Sir Robert suffers from a nervous temperament throughout the play.
Sir Robert is a fairly static character, undergoing little development and ultimately receiving salvation through the machinations of Lord Goring. He does, however, give way to one major outburst once the balancing act between his secret past and ideal persona becomes untenable. Unmasked by Mrs. Cheveley at the end of Act II, he curses Lady Chiltern's impossibly worshipful love as causing their ruin: in other words, because of her worship he could not descend his pedestal, so to speak, and admit his crimes to her earlier. Sir Robert considers himself a victim of what he identifies as "feminine" adoration. In contrast, he loves in a "masculine" fashion—that he can love his lover's human imperfections and then forgive her faults. Sir Robert thus becomes the vehicle of one of the play's primary pronouncements on the theme of marriage. Like his wife, his is largely a melodramatic voice, the conventional nature of his speech—that is, conventional in terms of the popular Victorian stage—reflecting the conventional nature of its content.
Lady Chiltern is the play's upright and earnest heroine, embodying the ideal of Victorian new womanhood Wilde elaborated while editor of the Women's World magazine in the late 1880s. This new woman was best represented by an educated wife involved in women's issues and supportive of her husband's political career. Lady Chiltern certainly embodied these characteristics, and unlike Sir Robert, Lady Chiltern is not self-divided, but perfectly virtuous. Though a poised, charming, and dignified society wife, Lady Chiltern is naïve when it comes to the machinations around her. In this sense, she is Mrs. Cheveley's ready victim.
Lady Chiltern undergoes a rather simple development through the course of the play, specifically with respect to the theme of marriage and, more precisely, the question of how women should love. Toward the end of Act I, she melodramatically delivers a speech to Sir Robert that introduces the idea of the "ideal husband" and establishes the nature of her love, a love described from the outset as "feminine." As a woman, Lady Chiltern loves in the worship of an ideal mate, a mate who serves as model for both her and society at large. Thus she rejects Sir Robert upon the revelation of his secret past, unable to brook neither his duplicity nor the justification of his dishonesty as necessary compromise.
Ultimately she will learn from her counselor, Lord Goring, that the loving woman should not so much idealize the lover as forgive him his faults. Goring will also teach her that Sir Robert—as a man—lives by his intellect and requires a successful public life. Thus Lady Chiltern will forgo her rigid morals and allow her husband to continue his career despite its ill-gotten beginnings.
Foil to the earnest Lady Chiltern, Mrs. Cheveley is the play's femme fatale: bitingly witty, fabulously well dressed, cruel, ambitious, opportunistic, and, above all, duplicitous. Repeatedly the play describes her as the product of "horrid combinations," evoking her dangerous deceitfulness. Thus Lady Basildon recoils from her "unnatural" union of daytime genius and nighttime beauty; later, Cheveley appears as a "lamia-like" villainess—that is, part woman and part snake. Whereas Lady Chiltern is pure and undivided, Mrs. Cheveley is defined by deception, artifice, and falsehood.
Cheveley returns from Vienna as a sort of ghost from the past, at once an old enemy of Lady Chiltern's from their school days, the traitorous fiancée of the young Lord Goring, and a disciple of the deceased Baron Arnheim, Sir Robert's seductive corrupter. Even more than Sir Robert, she fiercely subscribes to Arnheim's philosophy of power and gospel of wealth, treasuring the domination of others above all. Thus she unscrupulously wreaks havoc in the Chiltern's married life to secure her fortunes and dismisses marriage as a mere transaction. Thus, within the moral scheme of the play, she stands opposed to the sentimental notions of conjugal life embodied by the Chilterns and Lord Goring.
With this in mind, Mrs. Cheveley's undoing in Act III avenges her crimes against the conjugal household. Called to account for a past crime, she finds herself trapped for a stolen wedding gift—the diamond brooch—by her ex-fiancé. The poetic justice in her arrest is clear. Moreover, this undoing also unmasks her as a monster. Once trapped by Lord Goring, Cheveley dissolves into a "paroxysm of rage" her loss of speech giving way to an agony of terror that distorts her face. For a moment, a "mask has fallen," and Cheveley is "dreadful to look at." Her veneer of wit and beauty thus give way to the hidden beast.
Described as the first well-dressed philosopher in history, Goring is the dandified hero of the play and a thinly veiled double for Wilde himself. As the stage notes from Act III indicate, he is in "immediate relation" to modern life, making and mastering it. He thus serves as bearer of Wilde's aestheticist creed stressing amorality, youth, pleasure, distinction, idleness, and onward in rebellion against Victorian ideals. An Ideal Husband emphasizes Goring's modernity by posing him in a number of comic dialogues with his father, Lord Caversham—in which the former urges his son to marry and claim responsibility while the latter outwits him with his repartee.
Within the play's moral scheme, Goring delivers a number of the play's more sentimental pronouncements on love and marriage, serving as helpmate to the Chilterns and teacher to the impossibly upright Lady Chiltern in particular. Thus he extols the importance of forgiveness and charity in married life, reconciling the Chilterns' marriage according to new ideals of man and wife. At the same time, however, his own union with Mabel Chiltern is far less conventional, dispensing with the questions of duty, respectability, and the ideal roles of man and wife entirely. Alike in their amoral posture, Goring and Mabel thus stand as foils to the Chilterns and their newly ideal marriage.