A gentleman and a friend of Aramant, Antonio teams up with Aramant's other friend, Trebutio, to introduce the play, discuss the nature of women, make fun of Pantarbo, find Aramant in the forest, and provide narrative links and character sketches throughout the play. When Cloris escapes from confinement by Emilia through the garden gate, Antonio enters the garden and confronts Emilia with a charge that she is false and inhumane.
ARAMANT
A young nobleman at the court of the Duke of Burgundy, Aramant adores Emilia and wishes to marry her. Unfortunately, his father disapproves of Emilia, and forces Aramant to choose between her and his inheritance. Aramant chooses Emilia, and his father dies, leaving the entire estate to Aramant's younger brother, Millecert. Seeing Armant disinherited, the inconstant Emilia abandons him in an instant and woos Millecert. Enraged at learning the two are to wed, Aramant draws his sword on Millecert and has to be restrained by Serius and Tonsus. Disinherited and jilted, a despondent Aramant wanders into the forest where he meets Cloris and is immediately smitten. She sings him to sleep but disappears before he wakes. Later he finds her at the palace where the Duke has confined her, intending to make her his wife. With the help of Gratus, who is really his brother, Millecert, in disguise, Aramant helps Cloris escape from the palace. Later, when the Duke learns that Cloris is actually the daughter he thought dead, the Duke bows to Cloris' pleas and allows Aramant and Cloris to marry.
BELLAURA
Bellaura, daughter of the Duke of Burgundy, was left as an infant to die in the Grove of Cloris on Busario's orders. A witch had reportedly told Busario that Bellaura would be his ruin. When Bellaura disappeared, the trusted Busario convinced the Duke and all his court that she had died of an abscess. In fact, she was discovered alive by Emilia's father and raised as her sister with the name of Cloris. As Emilia's father lay dying, he told her that Cloris was not her biological sister, but neither Emilia nor her father knew that the Duke was Cloris' real father. Cloris knew none of this. Only in the concluding scene does Cloris, the Duke, Emilia, and the rest of the court discover that Cloris is the grown up Bellaura.
BUSARIO
Lord Busario, the old and trusted right-hand man of the Duke of Burgundy, has killed all of his rivals and potential rivals, including, he believes, the Duke's daughter and heir, Bellaura. His guilty conscience leads him to frequent the whorehouse of Madame Romilia, also a haunt of his son, Pantarbo. Ignorant of all of this, the Duke entrusts Busario to guard Cloris, whom the Duke locks her in the palace in hopes of making her his wife. Busario, in turn, employs Gratus to woo Cloris for the Duke. Gratus, gradually realizing that Cloris is really Bellaura, explains this to the Duke in Busario's presence. To avoid torture after this revelation, Busario confesses, and the Duke banishes him from the realm and confiscates his property. Before he leaves Busario is shamed once more by learning that Pantarbo has outwitted himself into marrying Romilia.
CLORIS
The attractive noblewoman, Cloris, is locked in her room by her sister, Emilia, who is jealous of her beauty. When Emilia abandons Aramant for Millecert, Cloris takes pity on Aramant and her pity grows into love. When Lavia frees her from confinement, Cloris seeks out Aramant in the forest, disarms him with her words and beauty, and sings him to sleep. The Duke of Burgundy, out hunting, happens upon the couple and is stricken by Cloris' beauty and noble behavior. Desirous of making her his duchess, the Duke orders Cloris to the palace where he confines her and begins to woo her. She diplomatically tries to talk him out of loving her, but his goodness and virtue make her love and admire him. Endeavoring to block this marriage, jealous Emilia confides to Gratus that Cloris is not her biological sister but rather an adoptee of unknown parentage and therefore unworthy of the Duke. Gratus helps Cloris escape the palace in Aramant's care, telling the Duke that she has died of poisoning. In the final scene Gratus reveals that Cloris is really Bellaura, the Duke's own daughter and heir, a startling revelation not only to the Duke, but also to Aramant, Emilia, and Cloris herself. Cloris persuades her newly found father to allow her to marry Aramant.
DUKE of BURGUNDY
The Duke of Burgundy depends heavily upon Lord Busario for counsel and assistance in ruling his duchy, not knowing that Busario is a murderous lecher who years earlier had abandoned the Duke's only child in the wild to die. While hunting one day the Duke, a widower, happens upon Cloris and is so taken by her beauty and nobility that he immediately decides to make her his wife. He takes her to his palace and locks her in a room under Busario's charge, hoping to persuade her to him. Busario appoints Gratus, the disguised Millecert, to guard Cloris and woo her on the Duke's behalf. When Gratus discovers that Cloris is really Bellaura and tells the Duke about it, the latter banishes Busario and confiscates all his worldly possessions. More importantly, the Duke consents to his daughter's marriage to Aramant and promises her a rich dowry. The Duke also restores Millecert's lands to him and persuades him to take Emilia back as wife. Addressing Emilia in the concluding line of the play, the Duke declares, "You, lady, have been inconstant; therefore, now endeavor a reformation--better late than never."
EMILIA
A noblewoman and sister of Cloris, Emilia is the inconstant lady of the play's title, an unfaithful wife and lover. She is set to marry Aramant until his father disinherits him and leaves the entire estate to Millecert, Aramant's younger brother. Emilia immediately dumps Aramant and charms Mellecert into becoming her husband instead. Jealous of Cloris' beauty, Emilia has kept her sister locked in her room since their father died. Cloris escapes while the guilt-ridden Millecert renounces his inheritance and disappears. When Emilia learns that the Duke intends on marrying Cloris, Emilia decides that she wants to become duchess herself. She urges Busario to employ Gratus to help the Duke woo Cloris, not knowing that Gratus is actually her own husband, Millecert, in disguise, scheming that Gratus will assist her in bedding the Duke. Seeking to prove Cloris unworthy to marry the Duke, she confides to Gratus that Cloris is not really her biological sister, but rather a stranger of unknown parentage. When Cloris escapes from the palace but believing her dead, Emilia gets into Cloris' bed, intending to seduce the Duke for herself. She tells Gratus both that she loves the Duke and that Millecert is a fool, offering to divide the spoils with him if he helps her become duchess. After Gratus reveals himself as Millecert, tells Cloris' story, recovers his wealth, and is persuaded by the Duke and his court to take Emilia back, the inconstant lady is reunited with her husband and promises theceforth to remain constant.
GRATUS
Millecert gives his inheritance to Aramant and disguises himself so successfully as Gratus that neither his wife, Emilia, nor his brother, Aramant, recognize him when they see him at the palace. The Duke of Burgundy employs Gratus to guard Cloris and to sweet talk her into becoming the Duke's wife. Instead, Gratus helps his brother, Aramant, free Cloris from captivity. Meanwhile, Emilia contacts Gratus for assistance in her quest to woo the Duke for herself. When Emilia, disguised as Cloris, meets the Duke in Cloris' cell, Gratus interrupts with the revelation that the woman in bed is really Emilia. After Emilia confides in Gratus that Cloris was adopted, and Busario confesses that he abandoned the Duke's infant daughter, Gratus concludes that Cloris is the Duke's daughter, long thought to be dead, and explains this to the Duke. In the concluding scene Gratus reveals himself as Millecert, and, at the Duke's urging, takes back his inconstant wife, Emilia.
LAVIA
Lavia is Emilia's servant, bringing Cloris to her on request, annouincing the arrival of Aramant and Millecert, and keeping Cloris locked in her room. She speaks honestly and directly to Aramant about Emilia's loss of love for him, and later she tells the admiring Cloris that Aramant is "[t]he most accomplish'd gentleman in Burgundy." She unlocks the gate for Cloris can escape to find Aramant, and then covers for her with Emilia. In the closing scene, Cloris remembers "honest Lavia."
MELA
A prostitute in Romilia's brothel, Mela helps prepare the house for Busario's visit, noting that his money keeps them in food and drink. In the midst of the orgy that the whores stage for Busario, Mela sings a wanton song declaring that she prefers old lovers to young ones.
MILLECERT
Millecert inherits the family estate when his father, angered that his older brother, Aramant, chooses to marry Emilia, disinherits Aramant, the rightful heir. Wanting the money more than the man, Emilia dumps Aramant and charms Millecert into marrying her. When he catches his wife and Pantarbo kissing, he draws his sword and injures Pantarbo. Shortly thereafter, his conscience leads him to give the ancestral estates to Aramant. He then disappears, secretly disguising himself as Gratus. After uncovering Cloris as the Duke's daughter, Millecert throws off the Gratus disguise, receives back his inheritance, and agrees to reunite with Emilia.
PANTARBO
A fop and libertine as well as Busario's son, Pantarbo spends most of his time memorizing lines he hopes will help him seduce women. He is as familiar as his father is with Romilia's brothel, so when he is injured by the aggrieved Millecert for kissing Millecert's inconstant wife, Pantarbo ends up in Romilia's care. When he uses his memorized speeches on her, he traps himself into marrying the madam.
ROMILIA
A madam who entertains both Lord Busario and his son, Pantarbo, Romilia ends up as Pantarbo's wife when she declares before the Duke of Burgundy that he is her husband and Pantarbo is forced to admit that this is true.
SERUIUS
A courtier who is often in Pantarbo's company, Seruius joins with Tonsus in making fun of Pantarbo's foppery. He also helps Tonsus separate Aramant and Millecert when Aramant draws his sword on his brother.
TONSUS
A courtier who banters with Seruius and joins him in making fun of Pantarbo and Busiro, Tonsus is often seen with Pantarbo but little heard. On Pantarbo's request he helps Seruius stop the brothers Aramant and Millecert from hurting each other when Aramant draws his sword after learning the Millecert has stolen Emilia from him.
TREBUTIO
A gentleman and a friend of Aramant Trebutio joins with Antonio to introduce the play and several characters, discuss the nature of women, be there to support Aramant, and generally provide a connective narrative throughout the play.