The novel's narrator and sidekick to Poirot, who provides a first-person account of the investigation, sharing similarities with Arthur Conan Doyle's Dr. Watson.

Dr. Sheppard's sister who relies on intuition and local knowledge, which significantly aids Poirot's investigation.

The victim of the murder around which the mystery revolves, sharing a past interest in uncovering blackmail against Mrs. Ferrars.

Roger Ackroyd’s sister-in-law, who acts as a caregiver for her niece Flora and remains a background character throughout most of the narrative.

Roger’s niece and the love interest of both Major Blunt and Ralph Paton, known for her role in unexpectedly driving parts of the investigation forward.

A guest at Ackroyd’s house and potential suspect whose connection with Flora encourages him to remain within society.

Ackroyd’s reliable secretary who becomes involved in the investigation but plays a minor role in the story's development.

A maid at Ackroyd's house with a secret concern, who briefly draws suspicion during the investigation.

A character tied to a key symbol in the mystery, providing crucial background information uncovered later in the story.

A frequently mentioned but physically absent character, whose whereabouts are central to the unfolding mystery.

The local police inspector working on the case who contrasts with Poirot in his approach and methodology.