Matilda: A beautiful young woman who is the object of Ambrosio's desire. She is eventually killed by Ambrosio after she rejects him.
Agnes: A young nun who is Ambrosio's pupil. She is seduced by Ambrosio and becomes pregnant. She eventually dies of childbirth.
Don Raymond: The abbot of the monastery where Ambrosio lives. He is a wise and just man who tries to help Ambrosio overcome his temptations.
Donna Elvira: A wealthy and powerful woman who becomes Ambrosio's lover. She eventually betrays him and turns him over to the Inquisition.
The Inquisitor: A powerful and ruthless man who presides over Ambrosio's trial and ultimately condemns him to death.