Young is a high school senior and the narrator of the story. He comes from a family of doctors and feels immense pressure from his rigid father to pursue medicine, though he secretly prefers writing fiction. As a member of the popular crowd, he often defers to his highly charismatic friend Rob, struggling to assert his own identity or stand up for his personal desires.

A confident transfer student who quickly claims the top spot in B'Vale High School's social hierarchy. Rob possesses an almost unnatural charisma that makes others eagerly want to follow and please him. He spearheads the project to transform the school's biggest outcast into its most popular student, motivated by a fierce need for control and a rivalry with the former king of the school.

Simon begins his senior year as the absolute lowest person on the school's social ladder, ridiculed for his weight and awkward clothing. Living in an opulent mansion largely ignored by his parents, he uses his solitude to master computer technology. When Rob offers to make him popular, Simon calculates the benefits and agrees to the transformation, revealing an unexpectedly sharp mind.

B'Vale's star linebacker and a central member of the popular crowd. Coop struggles academically and lives in constant fear of failing the ACT, which would ruin his chances of an athletic scholarship and trap him in his hometown. Despite his imposing physical size, he possesses a genuinely kind heart and is the first of the group to show sincere sympathy toward Simon.

A handsome, flirtatious member of the high school's popular clique. Bobster thrives on projecting an image of toughness and maintaining a steady rotation of girlfriends, though his bravado often masks underlying cowardice. He actively participates in the plan to elevate Simon's social status, taking charge of teaching him how to drive.

A sharp, intelligent student who catches Young's attention. Ronna values authenticity and proves highly perceptive about the shifting social dynamics at her high school. She questions the true motives behind the boys' sudden interest in Simon and challenges Young to think for himself rather than blindly following Rob's directives.

The former king of B'Vale High's social scene before Rob's arrival ousted him from the top spot. Lance relies on mean-spirited bullying and belittling the weakest students to maintain his status. Angry and embittered over losing his popularity and his girlfriend, he serves as the primary target for Rob's social warfare.

A popular, attractive girl at the high school who previously dated Lance before leaving him for Rob. She enjoys her comfortable status at the top of the social hierarchy but occasionally notices Rob's darker, colder tendencies.

Widely considered the most unpopular girl at B'Vale High School. She becomes an unwitting pawn in the social games played by the popular students, manipulated into publicly pursuing Lance in a way that humiliates him.

The principal of the high school, affectionately known by the students as "Deputy Dog." He generally views the boys' integration of Simon into their group as a positive, generous act of school spirit, remaining entirely unaware of their underlying motives.

The high school counselor who assists students with their course schedules. She is overworked and easily distracted, making her susceptible to the boys' schemes to bypass school rules and hack the system.

The school cafeteria worker who harbors a deep dislike for the popular crowd. She sees through their superficial charm and views the boys as spoiled, disrespectful troublemakers.

Simon's mother, who lives in a sprawling mansion but remains emotionally distant from her son. She prefers the quiet of her personal wing and shows little interest in Simon's daily life until his sudden surge in popularity catches her attention.

Simon's wealthy but largely absent father. He provides his son with immense financial resources, including top-tier computer equipment and a brand-new car, but offers zero genuine parental guidance or affection.

A successful, demanding doctor who exerts strict control over Young's future. He insists that his son follow in his footsteps by pursuing a medical career, showing absolutely no regard for Young's passion for creative writing.

A former high school gridiron star whose life peaked in his youth. Now an overweight alcoholic working a dead-end job, he serves as a living cautionary tale for Coop, driving his son's desperation to secure a college scholarship at any cost.

A student at the high school known for prizing physical prowess over reputation. She becomes involved in the boys' social machinations when Rob decides she should be Young's new date to clear the path for Simon.