Madame de Clèves (Mademoiselle de Chartres)
Madame de Clèves is the ethereally beautiful female protagonist of the novel. She was sheltered from a young age, only exposed to society when she reached sixteen. She is the daughter of Madame de Chartres and was arranged to be married to M. de Clèves who is utterly in love with her. She secretly holds affection for M. de Nemours. Throughout the novel, she battles between the sense of duty as a loyal wife and her own yearnings and desires of true love.
M. de Clèves
M. de Clèves is the Prince of Clèves and not the eldest of his family. He is the first to see Madame de Clèves and falls in love with her beauty and modesty immediately. He marries her but is often insatisfied with her lack of passion in their love. He dies shortly (most likely out of mental grief and jealousy) after discovering his wife's affection for M. de Nemours. His last request before he died was that his wife stay faithful to him and not marry M. de Nemours.
M. de Nemours
M. de Nemours is an extremely handsome, skilled, "playboy" nobleman who is very popular amongst women in the court. He met Madame de Clèves at a ball and danced with her. They fell in love with each other very quickly. He is completely and passionately in love with her, to the point of stealing a portrait of her to keep.
Madame de Chartres
Madame de Chartres is the mother of the Madame de Clèves. After her husband died, she devoted her entire life to raising her daughter into a proper wife-worthy noblewoman. Upon her deathbed, she requested that her daughter hold back her feelings for M. de Nemours for the safety of social status and reputation.