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.