She Stoops to Conquer by Oliver Goldsmith is a play with many characters and subplots, making it difficult to follow when it is read rather than performed. While different characters feature in different subplots, Kate Hardcastle is the main character linking these together and the protagonist of the central plot.
Kate Hardcastle is the character with whom the audience sympathizes the most. The central plot revolves around her trying to find a husband who will be compatible with her rather than just one of the right social class. The other marriage and love plots in the play serve mainly as foils to the central plot. Constance is similar to Kate and her plot runs in parallel with Kate's; she takes on the typical "best friend" role in the play. Mrs. Hardcastle acts as the stock character of the "matrona" serving as an obstacle to Constance's romance. Tony Lumpkin is the antagonist. Hastings and Marlow play the role of suitors, but are depicted as far less interesting, determined, and clever than the two girls.
Kate is the most dynamic and well-rounded character in the play and the one most transformed over its course.
While the characters tumble over each other in this play of mistaken instructions, mistaken behavior and mistaken identity, the real story centers around Kate Hardcastle. Kate is determined to marry for love, and not for social standing or convenience. She is the title character, and she 'conquers' Marlow's heart by fooling him into revealing his generous and unbiased nature. She undergoes a change, from disliking him to truly respecting and loving him, and in that change she sees the importance of crossing the boundaries of class and society. She manipulates the situation and she wins out in the end. With the action centering around her, Kate is the protagonist.