Beth is a young orphan who discovers a prodigious talent for chess while living in Kentucky. She deals with deep feelings of isolation and anxiety, which she temporarily suppresses through a growing dependence on the orphanage's green tranquilizer pills. Highly competitive and resourceful, she dedicates her time to mastering chess strategy and visualizing moves on the ceiling at night.

Vasily is the Russian grandmaster and reigning world chess champion. He plays with a disciplined, emotionless style that terrifies his opponents, embodying the formidable Soviet chess machine. He represents the ultimate competitive hurdle for ambitious players worldwide.

Jolene is an older Black girl living at the Methuen Home who bonds with Beth over their shared struggles with the adoption system. She provides practical advice to the younger girls and acts as a protective, if occasionally harsh, guide for Beth. Confident and athletic, she makes plans for her own future away from Kentucky.

Mr. Shaibel is the quiet, introverted janitor at the Methuen Home. He plays chess alone in the basement and eventually agrees to teach the persistent young Beth the rules, openings, and notation. He serves as Beth's introduction to the wider world of competitive chess.

Alma is Beth's adoptive mother, a housewife who deals with an unhappy marriage and a distant husband. She copes with her isolation through alcohol and the same green tranquilizers Beth knows from the orphanage. After discovering that chess tournaments offer monetary prizes, Alma actively manages Beth's travel across the country.

Harry is the confident, casual Kentucky State Chess Champion. He initially underestimates Beth due to her age and gender but quickly realizes her formidable skill. He possesses a traditional understanding of chess theory and studies the game extensively through books.

Benny is the US Chess Champion and a former child prodigy himself. He is a highly skilled, tactical player who excels particularly at speed chess. Confident and occasionally abrasive, he challenges Beth's aggressive playstyle and forces her to consider deeper strategic calculations.

Allston is Alma's husband and Beth's adoptive father. He is frequently away on business trips and shows no genuine interest in his wife or his newly adopted daughter, treating the adoption as an unsuccessful attempt to placate Alma.

Townes is an attractive older chess competitor who catches Beth's eye early in her career. He possesses a gentle, encouraging demeanor and later works as a journalist for Chess Review magazine, combining his passion for the game with reporting.

Mrs. Deardorff is the strict superintendent of the Methuen Home. She enforces the orphanage's rigid rules, manages the distribution of the green pills, and dictates severe punishments for infractions.

Mr. Ganz runs a local high school chess club and is a friend of Mr. Shaibel. After being thoroughly defeated by Beth, he arranges for her to play against his entire high school team simultaneously.

Luchenko is a respected, older Russian grandmaster competing in the Moscow invitational. Unlike some younger competitors, he treats his opponents with courtly respect and deep appreciation for the game.

Jenny is a beautiful and intelligent friend of Benny Watts in New York City. She observes Beth's incredible skill at speed chess with genuine admiration, representing an environment where Beth's intelligence is celebrated.

Margaret is a popular student at Beth's junior high school and a member of the exclusive Apple Pi Club. She represents the conventional adolescent social hierarchy that Beth finds difficult to handle.