Devin is a 21-year-old college student at the University of New Hampshire who takes a summer job at the Joyland amusement park in 1973. Heartbroken over a recent breakup, he channels his energy into his work as a "Happy Helper" and finds deep satisfaction in wearing the "Howie the Happy Hound" mascot costume to entertain children. Naturally curious and deeply empathetic, he becomes fascinated by local park legends while forming close bonds with the local residents.

Annie is a beautiful but withdrawn woman living in a large house near the beach in Heaven's Bay. A former champion markswoman who dropped out of college, she isolates herself from the outside world to focus entirely on caring for her chronically ill son. She projects a cold, defensive exterior to protect herself from impending grief and the judgments of others.

Mike is Annie's young son, who has Duchenne muscular dystrophy and uses a wheelchair. Despite his physical frailty and a grim medical prognosis, he possesses an extraordinary, intuitive clairvoyance. He remains cheerful and highly perceptive, often understanding things about people and situations that adults try to hide from him.

Lane is the charismatic operator of the Carolina Spin Ferris wheel at Joyland. He is an experienced carnival worker who wears a signature derby hat tilted to the side. He acts as an informal mentor to the new summer hires and enjoys sharing the park's macabre local legends with newcomers.

Linda is a young woman who was killed during a ride through the Joyland Horror House four years before Devin's arrival. Her unsolved murder casts a long shadow over the park, and local legend suggests her spirit remains trapped inside the dark ride. Her story captures the imaginations of the summer hires, representing unresolved grief and unfinished business.

Erin is a college student working at Joyland as a "Hollywood Girl," photographing park guests for souvenirs. Sensible and helpful, she forms a tight-knit trio with Devin and Tom during the summer. She uses her access to university resources to assist Devin in researching the park's dark history.

Tom is a college student working at the amusement park who holds a more cynical and worldly view than Devin. He is pragmatic about money and rewards, pushing Devin to value himself higher. A deeply unsettling experience in the Horror House profoundly challenges his skeptical worldview.

Wendy is Devin's first love and college girlfriend. She takes a summer job in Boston with a friend rather than staying with Devin, eventually sending him a dismissive breakup letter. She represents Devin's lost innocence and the painful transition out of adolescence.

An older woman whose real name is Rozzie Gold, working as the resident fortune teller at Joyland. While many of her readings are standard carnival fare, she possesses genuine moments of clairvoyance. She refuses to go near the Horror House due to her strong belief that it is truly haunted.

The proprietor of a local boarding house in Heaven's Bay where several summer workers stay. She is a long-time resident who knows the history of the town and the amusement park intimately, providing Devin with the chilling details of the Horror House murder.

A gruff, bitter older employee at Joyland who supervises the maintenance and winterization of the park. He constantly wears gloves to cover up his severe psoriasis. Beneath his foul temper lies a deep personal grief over the loss of his family.

The elderly owner of Joyland amusement park. He holds an idealistic view of the park, believing that providing people with a brief escape from the broken world is a noble calling. He values employees who understand the importance of selling happiness.

A charismatic television evangelist with a thick shock of white hair. He is Annie's father and believes that his grandson's severe illness is divine punishment for Annie's past behavior, causing a deep, painful rift between them.

A little girl visiting the park wearing a distinctive red hat. Her life is saved when a quick-thinking park employee performs the Heimlich maneuver, an event that brings significant positive press to Joyland.

The manager of Joyland who handles the day-to-day operations and hiring. He is practical but capable of great kindness, especially when it comes to organizing special events for park visitors who need them most.

A loyal Jack Russell terrier belonging to Mike. He is highly protective of the boy and serves as a natural icebreaker between Devin and the otherwise secluded family.