Lara Jean Song-Covey

Lara Jean, the protagonist, is a sixteen-year-old middle child. She is a hopeless romantic and shy; she feels a lot of pressure to fill her sister Margot’s shoes as the oldest daughter in the house (Margot has gone away to school). She has written letters to her previous crushes which she keeps in a box in her closet. Unbeknownst to her (and to the readers), her younger sister, Kitty, sends the box's contents to the boys to whom they are addressed. She has to deal with the fact that the letters are out, and eventually finds an unusual relationship in Peter Kavinksy, one of her childhood crushes. She gains confidence and perspective throughout the story that pushes her to take risks. 

Peter Kavinsky

Peter is Lara Jean's "fake" boyfriend throughout the majority of the novel. He is popular, sporty, and surprisingly kind. They begin dating as a means for Lara Jean to avoid coming to terms with her feelings for Josh, of which he, too, is informed from an old letter. Peter has an ex-girlfriend, Genevieve, whom he is initially trying to make jealous; however, his feelings for Lara Jean become sincere, as are hers for him.

Josh

Josh is Lara Jean's secret love interest at the beginning of the novel. The two have been friends since childhood, but Josh started dating Lara Jean's older sister, Margot, once they were in high school. Josh was caught off guard when Margot broke up with him in order to cut ties before attending college abroad. Josh and Lara Jean remain friends, and Margot becomes jealous when she realizes, upon returning from college, that Josh has demonstrated protective feelings for her sister. Josh had also received a letter from Lara Jean, prompting her to pretend to be with Peter.

Margot 

Margot is Lara Jean's older sister, who broke up with Josh at the advent of going to school abroad in Scotland. She is unaware that her sister ever had feelings for Josh until she learns of the letters.

Kitty

Kitty is the younger sister of Margot and Lara Jean. She is inspired to send out the hidden letters when Lara Jean finds out Kitty has a childish crush on Josh. 

Genevieve

Genevieve is Peter’s ex-girlfriend and the main antagonist in Lara Jean’s life. She and Peter have a tumultuous on-again, off-again relationship. The rumor is that Genevieve cheated on Peter with an older college boy. When she notices how close Peter and Lara Jean have gotten, she attempts to sabotage them. She is the classic “mean girl” archetype who is well known for making people miserable to benefit herself. Genevieve seems to be more dynamic than initially perceived, and there are indicators that she is insecure and jealous of her former friend, Lara Jean.

Chris

Chris (or Christine) is Lara Jean’s best friend. She is also Genevieve’s cousin—the two absolutely despise one another. Unlike Lara Jean, Chris is outgoing and a bit of a partier.  She is sexually active and has tried drugs. She is very supportive of Lara Jean’s relationship with Peter and approves of her going outside her comfort zone. She also wants to get back at her cousin, and thus encourages Lara Jean to keep making Genevieve angry.