Cooper is a 12-year-old middle school student who moves frequently due to his father's military career. Struggling to fit in at his fifth school in three years, he is nicknamed "Whatshisface" by his classmates. He possesses a glitchy, expensive GX-4000 smartphone that serves as his primary connection to a mysterious historical figure.

Roddy is a 13-year-old ghost from 1596 who lives inside Cooper's malfunctioning smartphone. Originally a printer's apprentice in Elizabethan England, he dreams of being recognized as a famous playwright. He possesses a sharp tongue, an expansive 16th-century vocabulary, and a deep resentment for William Shakespeare.

Jolie is an independent seventh-grader at Stratford Middle School who loves extreme sports like kiteboarding and rock climbing. She is cast as Juliet in the school's production of Romeo and Juliet. Unlike many of her peers, she makes an effort to learn Cooper's actual name and values honesty.

Brock is an obnoxious, attention-seeking seventh-grader and the primary bully at Stratford Middle School. He constantly mocks Cooper, calling him "kid" or "Whatshisface." Cast as Romeo in the school play, he frequently yells out inaccurate Shakespeare lines to keep the spotlight on himself.

Somerset Wolfson III is an eccentric billionaire who controls much of Stratford due to his immense wealth. Obsessed with William Shakespeare, he forces the middle school to perform the Bard's plays annually. He maintains a private, heavily guarded museum on his estate, rumored to house illegally acquired Elizabethan artifacts.

Veronica is Cooper's 16-year-old sister who quickly adapts to their new life in Stratford. Unlike her brother, she immediately joins the volleyball team and the yearbook committee, establishing a thriving social life. She often acts as a counterweight to Cooper's struggles with social isolation.

William Shakespeare is the famous Elizabethan playwright whose legacy dominates the town of Stratford. While revered as a genius by modern society, he is remembered by Roddy as a mediocre talent and a fraud who frequented the printing shop where Roddy worked.

Captain Vega is Cooper and Veronica's father, an active-duty member of the U.S. Army. His military career requires the family to relocate frequently, directly causing Cooper's difficulties in finding a permanent social group.

Mrs. Vega is Cooper and Veronica's mother. She frequently coordinates the family's busy schedule around her husband's military reassignments and tries to manage the household during their frequent moves.

Mr. Marchese is Cooper's homeroom teacher and the stressed director of the annual seventh-grade Shakespeare production. He is constantly anxious about the play's success and carries his script everywhere, fearful of displeasing the wealthy Somerset Wolfson III.

Aiden is a seventh-grade student at Stratford Middle School who runs in the same social circles as Brock. He participates in the school play and frequently joins in on mocking Cooper's lack of athletic and social standing.

Chad is a high school student and Brock's older brother. He dates Cooper's sister, Veronica, creating an awkward intersection between Cooper's family life and his problems at school.

Alistair Northrop was Roddy's father, an eccentric 16th-century inventor. After his wife died of the bubonic plague, he immersed himself in his work, creating early concepts for modern technology before authorities executed him under accusations of witchcraft.

Mary Northrop was Roddy's mother. She worked as a laundress in 16th-century London before dying of the bubonic plague when Roddy was a young child.

Ursula was the daughter of Rupert Mannering, the abusive printer who employed Roddy in 1596. She served as the inspiration for the heroine in Roddy's original manuscript, though Roddy always felt his social status was too low for her.

Rupert Mannering is a 16th-century printer who co-owned the shop Mannering and Brown. He worked Roddy relentlessly but inadvertently exposed the boy to the world of playwriting by printing scripts for visiting authors.