Barbara
The main protagonist of the play, Barbara is a major for the Salvation Army at the beginning of the play. She is a charming, vibrant young woman who begins to shift her extremely religious beliefs to participate in more pragmatic deeds to help the poor. Her father, the arms dealer, is the one who triggers this transformation.
Andrew Undershaft
Andrew is Barbara's father, an extremely prominent European arms industrialist who controls major manufacturing districts. He returns rather unexpectedly to Barbara's life, as he has always been distant and reserved to his family, and it is his arrival that determines how Barbara's world view will shift from the belief that God controls everything to the belief that in fact, it is the wealthy who do.
Adolphus Cusins
Adolphus is Barbara's suitor, determined to marry her. He studies plays, particularly those of Euripides, an ancient Greek playwright, and is fascinated with the tales of Dionysus and the madness they portray. He joins the Salvation Army to become closer to Barbara, but eventually falls for Andrew's ideals.
Lady Britomart Undershaft
Lady Britomart Undershaft is a practical, experienced lady of the upper gentility class. She is a character of polar opposites, polite and well-spoken, yet also insolent at times with her speech. However, she serves too concrete with her thinking, and is rejected for Andrew's plans.