Cora is a 16- or 17-year-old enslaved girl living on the Randall plantation in Georgia. Following the disappearance of her mother, she endures severe isolation and abuse, claiming an old hatchet to defend her small garden patch from other enslaved people. She maintains a hardened, pragmatic exterior but possesses deep compassion, which she demonstrates by shielding a young boy from a brutal beating. This protective act leads to severe punishment and ultimately motivates her to flee the plantation.

Ridgeway is a massive, six-and-a-half-foot-tall slave catcher with a square face and a serene yet ominous demeanor. The son of a blacksmith, he believes in a philosophy he calls the American imperative, viewing the subjugation of Black and Indigenous people as a divine right of white conquerors. He operates a specialized posse and treats his profession as a personal crusade.

Terrance is the younger son of Old Randall and assumes control over the plantation. He is notably ruthless, implementing new torture devices and increasing labor quotas. He views the enslaved people purely as assets to be squeezed for maximum profit and submission, extracting brutal punishments to maintain absolute authority.

Caesar is an enslaved man who was recently brought to Georgia from Virginia. On his previous farm, he experienced a less brutal environment, learning to read and practice woodworking. The harsh reality of the Randall plantation pushes him to secretly coordinate an escape with a local abolitionist sympathizer. He selects Cora as his travel companion, believing her inner strength is essential for their survival.

Mabel is Ajarry's only surviving child and Cora's mother. She holds a legendary status on the Randall plantation as the only enslaved person to ever successfully escape the property. Her absence leaves a profound psychological impact on Cora and creates a permanent blemish on Ridgeway's professional record.

Elijah is a famous biracial abolitionist and orator. Educated at a prestigious white institution in Boston, he uses his academic gifts to travel the country speaking about Black unity and human rights. His elegant, calm demeanor masks the radical force of his public speeches, which draw both large crowds and violent opposition.

Ajarry is Cora's grandmother, who survived a harrowing journey across the Atlantic and multiple auctions before arriving at the Randall plantation. She learned to mind her place and assess her surroundings to survive. She claimed a three-yard square of dirt at the end of the cabin row, passing down this tiny inheritance to her family.

Lovey is Cora's friend on the Randall plantation. She has a whimsical, fussy personality and openly displays her desires, contrasting with Cora's guarded nature. When she discovers Cora and Caesar's escape plan, she impulsively decides to follow them into the Georgia swamps.

Fletcher is a hunched, gray-haired white merchant originally from Pennsylvania. Appalled by the institution of enslavement, he risks his life to operate as a local contact for the Underground Railroad in Georgia. He earns Caesar's trust and helps initiate the journey north.

Sam is a 25-year-old white bartender and Underground Railroad station agent in South Carolina. He hides the entrance to the railway beneath his barn. He uses his position at a local saloon to gather town gossip and monitor potential threats to the fugitives he helps conceal.

Martin is a nervous, barrel-shaped white man who inherited his role as an Underground Railroad agent from his late father. Living in North Carolina, where harboring fugitives is punishable by death, he operates under immense anxiety. He hides Cora in a small attic hatch above his home.

Ethel is Martin's wife. She deeply resents the danger her husband brings to their household by harboring fugitives. During her childhood, she developed a savior complex, fantasizing about working as a missionary to convert Black people. This manifests in a strange, controlling attitude toward Cora when Cora falls ill.

Homer is a ten-year-old free Black boy who travels as part of Ridgeway's posse. Ridgeway purchased him to settle a debt and then emancipated him, but Homer chose to stay. He functions as the group's bookkeeper, recording Ridgeway's accounts and speeches in a small notebook.

Boseman is a rough former dockhand and gravedigger from South Carolina who makes a living as a slave catcher. He serves as Ridgeway's subordinate and wears a gruesome necklace of human ears. He uses violence casually and attempts to assault Cora during their journey.

Royal is a freeborn Black man from Connecticut who works as a dedicated operative for the Underground Railroad. He utilizes his confident demeanor and white-passing privilege to execute daring rescues and purchase land for Black communities. He brings Cora to the Valentine farm and gradually earns her trust.

John Valentine is a biracial man with Ethiopian ancestry who passes as white. He uses this social advantage to build a massive, thriving agricultural community for Black freemen and runaways in Indiana. He frequently hosts debates in his home regarding the future of Black Americans.

Mingo is a stout resident of the Valentine farm who secured his own family's freedom through weekend labor. He represents a conservative faction on the farm, arguing that the community should stop harboring fugitives to appease the surrounding white towns and secure economic stability.

Gloria is John Valentine's wife. Formerly enslaved on an indigo plantation, John purchased her freedom and married her. She acts as the social anchor of the Valentine farm, possessing the polished manners of a society lady while helping to manage the massive community.

Connelly is the aging Irish overseer at the Randall plantation. He is responsible for maintaining order in the fields and executing the brutal punishments demanded by the Randall brothers. He elevates certain enslaved men, like Moses, to enforce his will.

Chester is a young boy on the Randall plantation whose parents were sold when he was an infant. He possesses an unblemished joy that Cora wishes to protect. When he accidentally soils Terrance Randall's sleeve, Cora shields him from the ensuing violence.

Miss Lucy is a diligent white proctor in South Carolina who manages the Black women's dormitories. She presents herself as an advocate for racial uplift, managing Cora's job placements while quietly supporting the state's dark medical agendas.

Dr. Stevens is a Northern doctor in South Carolina. He examines Cora at the new hospital and attempts to persuade her to undergo a surgical sterilization procedure, framing it as a choice for her own destiny.

Red is a tall, muscular Underground Railroad operative from North Carolina. He fled north after his wife and son were murdered by regulators, transforming his grief into a sinister resourcefulness as he executes armed missions for the network.

Sybil is a slender, resilient woman who successfully fled enslavement with her young daughter under the light of a full moon. She shares a cabin with Cora and creates a serene domestic life that moves Cora deeply.

Fiona is the young Irish house girl employed by Martin and Ethel in North Carolina. She resents her employers and keeps a sharp eye on their odd behavior, eventually causing catastrophic problems for the household.

Carpenter is a towering, uneducated Irish body snatcher operating in South Carolina. He illegally digs up corpses, specifically targeting Black cemeteries where families lack the legal authority to protect their dead, and sells them to medical students.

Jasper is an enslaved man who fled a Florida cane field before being captured by Ridgeway in Tennessee. He refuses to communicate normally or eat, choosing instead to ceaselessly sing spirituals despite suffering physical abuse from the posse.

Lumbly is a cryptic Underground Railroad station agent in Georgia. He maintains a massive subterranean train platform beneath his farm and serves as Cora and Caesar's first guide into the actual tunnels of the railroad.

James is the older Randall brother who manages the southern half of the plantation. He prefers a slower, steadier approach to management than his brother and frequently travels to New Orleans to fulfill his cruel impulses in brothels rather than in the fields.