Kate Hardcastle is the protagonist of She Stoops to Conquer. She is described as beautiful and well-mannered, although both Marlow and Tony Lumpkin mention that she is tall when trying to insult her. When Marlow attempts to dismiss his love for her, he describes her as a “tall squinting lady” (89), although he clearly finds her very attractive when she is dressed as a bar-maid.

Kate is the daughter of Mr. and Mrs. Hardcastle, an upper-class family who have a good reputation and a noble lineage, but who are not particularly wealthy. They live in the countryside, but Kate has spent some time in London where she has developed a taste for modern fashion. Mr. Hardcastle complains about Kate's fashionable clothing, exclaiming when she first appears, “dressed out as usual, my Kate. Goodness! What a quantity of superfluous silk has thou got about thee, girl!” (8). However, unlike her half-brother Tony Lumpkin, Kate finds ways to bargain with her father rather than to outright defy his wishes. She demonstrates that she is persuasive, yet moderate, when she convinces her father to allow her to wear the clothing she likes for part of the day and to choose a husband that she prefers.