Arnie is a quiet, socially isolated high school senior who struggles with severe acne and a lack of self-confidence. He maintains strong relationships with his academic parents and his best friend Dennis, but his sudden obsession with his new car begins to change his personality and alienate him from his loved ones. As he restores the vehicle, he adopts an increasingly hostile, anti-social attitude.

Dennis is Arnie's best friend and a popular high school senior who plays on the local football team. Sarcastic but fiercely loyal, Dennis worries about Arnie's sudden infatuation with the new car, sensing an unnatural aura around the vehicle. He attempts to protect his friend from the isolating influence of the Plymouth Fury.

Rollie is an elderly, misanthropic war veteran who originally owned the Plymouth Fury. He harbors intense hostility toward the world, frequently using racist and sexist language to describe anyone who crosses him. His bitter spirit deeply influences the car he leaves behind for Arnie.

Leigh is an attractive new student who quickly forms a romantic connection with Arnie. She values independence and healthy relationships, making her increasingly uncomfortable with Arnie's fanatical devotion to his car. She quickly realizes that the vehicle exhibits an unnatural possessiveness over her boyfriend.

Christine is a red 1958 Plymouth Fury initially owned by Rollie LeBay. More than just a machine, the car exhibits an unnatural presence and demands absolute devotion from her owner. She violently rejects any outside relationships that might interfere with her bond to Arnie.

Darnell is a disreputable older man who runs a crude, messy garage where locals work on their vehicles. Involved in various illegal operations, Darnell provides Arnie with a space to keep the car while employing the teenager to help move illicit goods.

Regina is Arnie's mother and an English instructor at Horlicks University. Coming from a stoic, working-class background, she is deeply distressed that Arnie spent his college savings on a rundown vehicle, leading to bitter household conflicts.

Michael is Arnie's mild-mannered father who teaches history at Horlicks University. He often attempts to act as a peacekeeper between his stubborn wife and his equally stubborn son, trying pragmatic compromises to calm the household.

Buddy is an aggressive, older high school student who spends most of his day in shop classes. As the ringleader of a group of local miscreants, his hostility toward Arnie escalates from casual bullying to dangerous physical confrontations.

George is Rollie LeBay's younger brother. Unlike his bitter sibling, George is practical and straightforward, providing Dennis and Arnie with disturbing historical context about Rollie's violent past and the tragic events associated with the Plymouth Fury.

Rudolf is an intuitive state police detective investigating local crimes. He senses something inherently unnatural about the Plymouth Fury and remains deeply suspicious of Arnie's uncontestable alibis and secretive behavior.

Sandy is a friend of Buddy Repperton who works at the airport garage. Although he does not harbor personal malice toward Arnie, he yields to peer pressure and allows Buddy's gang access to vandalize the Plymouth Fury.

Moochie is one of Buddy Repperton's wayward high school friends. Economically disadvantaged and often seen begging for change, he eagerly participates in the escalating harassment against Arnie.

Kenny is Dennis's father, a tax consultant who formerly managed Will Darnell's finances. He maintains a warm, communicative relationship with his son and offers grounded advice regarding Arnie's newfound obsessions.

Elaine is Dennis's fourteen-year-old sister. She shares a lovingly teasing dynamic with her brother and heavily consumes pop culture.

Jimmy is an assistant at Will Darnell's garage who is generally considered unintelligent by the locals. He performs menial labor and occasionally interacts with Arnie during garage hours.

Dan is a member of Buddy's gang who helps run minor scams at his father's 24-hour gas station. He joins in the bullying and vandalism directed at Arnie's prized car.

Rick is a state detective who works alongside Rudolf Junkins. He assists in the broader investigation into Darnell's illegal syndicate and the strange events occurring around town.