Catherine Morland: A 17-year-old girl who loves reading Gothic novels. Something of a tomboy in her childhood, her looks are described by the narrator as "pleasing, and, when in good looks, pretty." Catherine lacks experience and sees her life as if she were a heroine in a Gothic novel. She sees the best in people, and to begin with always seems ignorant of other people's malign intentions. She is the devoted sister of James Morland. She is good-natured and frank and often makes insightful comments on the inconsistencies and insincerities of people around her, usually to Henry Tilney, and thus is unintentionally sarcastic and funny. (He is delighted when she says, "I cannot speak well enough to be unintelligible.") She is also seen as a humble and modest character, becoming exceedingly happy when she receives the smallest compliment. Catherine's character grows throughout the novel, as she gradually becomes a real heroine, learning from her mistakes when she is exposed to the outside world in Bath. She sometimes makes the mistake of applying Gothic novels to real life situations; for example, later in the novel she begins to suspect General Tilney of having murdered his deceased wife. Catherine soon learns that Gothic novels are really just fiction and do not always correspond with reality.
James Morland: Catherine's older brother who is in school at the beginning of the story. Assumed to be of moderate wealth, he becomes the love interest of Isabella Thorpe, the younger sister to his friend and Catherine's admirer John Thorpe.
Henry Tilney: A 26 year-old well-read clergyman, the younger son of the wealthy Tilney family. He is Catherine's romantic interest throughout the novel, and during the course of the plot he comes to return her feelings. He is sarcastic, intuitive, fairly handsome and clever, given to witticisms and light flirtations (which Catherine is not always able to understand or reciprocate in kind), but he also has a sympathetic nature (he is a good brother to Eleanor), which leads him to take a liking to Catherine's naïve straightforward sincerity.
John Thorpe: An arrogant and extremely boastful young man who certainly appears distasteful to the likes of Catherine. He is Isabella's brother and he has shown many signs of feelings towards Catherine Morland.
Isabella Thorpe: A manipulative and self-serving young woman on a quest to obtain a well-off husband; at the time, marriage was the accepted way for young women of a certain class to become "established" with a household of their own (as opposed to becoming a dependent spinster), and Isabella lacks most assets (such as wealth or family connections to bring to a marriage) that would make her a "catch" on the "marriage market". Upon her arrival in Bath she is without acquaintance, leading her to immediately form a quick friendship with Catherine Morland. Additionally, when she learns that Catherine is the sister to James Morland (whom Isabella suspects to be worth more financially than he is in reality), she goes to every length to ensure a connection between the two families.
General Tilney: A stern and rigid retired general with an obsessive nature, General Tilney is the sole surviving parent to his three children Frederick, Henry, and Eleanor.
Eleanor Tilney: Henry's sister, she plays little part in Bath, but takes on more importance in Northanger Abbey. A convenient chaperon for Catherine and Henry's times together. Obedient daughter, warm friend, sweet sister, but lonely under her father's tyranny.
Frederick Tilney: Henry's older brother (the presumed heir to the Northanger estate), very handsome and fashionable, an officer in the army who enjoys pursuing flirtations with pretty girls who are willing to offer him some encouragement (though without any ultimate serious intent on his part).
Mr. Allen: A kindly man, with some slight resemblance to Mr. Bennet of Pride and Prejudice.
Mrs. Allen: Somewhat vacuous, she sees everything in terms of her obsession with clothing and fashion, and has a tendency to utter repetitions of remarks made by others in place of original conversation.