A retired Belgian detective who has recently moved to King's Abbott to grow vegetables. He possesses an egg-shaped head and immense mustaches. Though he seeks a quiet retirement, his brilliant intellect and psychological insight quickly draw him into the local murder investigation. He values intuition and local gossip as much as physical evidence.

The town doctor of King's Abbott and the narrator of the story. He maintains a logical perspective on the world, frequently dismissing his sister's reliance on local rumors. As a respected pillar of the community, he acts as Poirot's primary companion during the investigation and records the unfolding events.

A wealthy widower and the most prominent citizen in King's Abbott. He supports various local organizations and serves as the financial backbone of his extended family. His sudden death in his locked study launches the central mystery of the novel.

Roger Ackroyd's young niece who lives at Fernly Park with her mother. She feels constrained by her dependence on her uncle's money and the societal expectations placed upon her. She actively pulls Poirot into the investigation when suspicion falls on her social circle.

Roger Ackroyd's handsome, charming stepson. He frequently struggles with finances and relies heavily on his stepfather's allowance. Following the murder, his sudden disappearance and a set of matching footprints make him the primary suspect in the eyes of the local police.

Dr. Sheppard's sister and the premier source of town gossip in King's Abbott. She stays at home but manages to learn almost everything happening in the village through an extensive network of rumors. Her sharp intuition frequently catches details that her logically minded brother dismisses.

Roger Ackroyd's widowed sister-in-law who resides at Fernly Park. She is highly conscious of social status and heavily reliant on Ackroyd's financial support. She frequently worries about maintaining appearances and securing an inheritance for her daughter.

A big game hunter and guest staying at Fernly Park. He feels out of place in polite English society and prefers the wilderness. Despite his discomfort with high society, his attachment to certain members of the household keeps him tethered to the estate.

Roger Ackroyd's young, capable secretary. He is cooperative, relatable, and maintains a generally pleasant demeanor while handling his employer's affairs. Like everyone in the house, he falls under Poirot's scrutiny following the murder.

The stern housekeeper at Fernly Park. She maintains a highly professional, guarded exterior while managing the estate's staff. She displays an unusual interest in poisons and drug addiction during a medical consultation shortly before the murder.

A parlourmaid at Fernly Park who comes from an impoverished family of seven. She took up service to support herself but finds the rigid class divides of the household difficult to manage. She harbors private anxieties regarding the social dynamics within the Ackroyd family.

The confident, traditional police inspector in charge of the Ackroyd case. He relies strictly on physical evidence, timelines, and standard procedural methods. He dismisses Poirot's unconventional inquiries and rushes to obvious conclusions regarding the suspect's identity.

The butler at Fernly Park. He is professional but exhibits nervous behavior when questioned by the police. He becomes an early suspect due to his presence near the study and his proximity to Ackroyd's private affairs.

A wealthy widow in King's Abbott whose recent death by a Veronal overdose sets the town's gossip mill in motion. Rumors suggest she poisoned her late husband and took her own life out of guilt.

A stranger from North America seen wandering the grounds of Fernly Park. He has a gruff demeanor, a drug addiction, and a connection to the estate that he attempts to keep hidden from the police.

A local police inspector who assists Raglan with the official investigation. He examines physical evidence on the estate grounds but generally defers to his superior's conclusions.