Arthur is a retired solicitor who writes down a traumatic experience from his youth to free himself from the memory. In his early twenties, he is an ambitious London professional engaged to Stella. He travels to the isolated town of Crythin Gifford to settle the estate of a deceased client, believing himself too sensible to be frightened by local superstitions or atmospheric gloom.

Samuel Daily is a wealthy, prominent landowner in Crythin Gifford who meets Arthur on the train. Unlike the rest of the villagers who refuse to speak about Eel Marsh House, he eventually offers Arthur practical assistance and company. He serves as a bridge between the pragmatic outside world and the deeply superstitious local community.

Jennet is a woman whose past is uncovered through old correspondence found at Eel Marsh House. She is the sister of Mrs. Drablow and the mother of a young boy named Nathaniel. Her letters reveal her extreme distress and anger over being forced to give her son up for adoption to her sister.

Alice Drablow is an elderly widow whose recent death sets the plot in motion. She lived entirely alone at Eel Marsh House, an estate cut off from the mainland by unpredictable tides. She leaves behind a chaotic mass of legal and personal paperwork, alongside an intensely private family history.

Mr. Bentley is the senior partner at the London law firm where young Arthur works. Aging and preparing for eventual retirement, he delegates the difficult task of sorting Mrs. Drablow's estate to Arthur. He views the assignment as a standard legal procedure, completely detached from the unsettling realities of Crythin Gifford.

Stella is Arthur's fiancé during his early years in London. She represents his bright, normal future and his ambitions for career advancement. Arthur hopes his successful handling of the Drablow estate will impress her and secure their life together.

Mr. Jerome is the local solicitor in Crythin Gifford who assists Arthur with the initial funeral arrangements. Though outwardly courteous and professional, he becomes extremely agitated and uncooperative when Arthur asks specific questions about the estate and its attendees, refusing to accompany him to the property.

Mr. Keckwick is a silent, stoic local man who drives a horse-drawn pony trap. He is responsible for transporting Arthur across the Nine Lives Causeway to Eel Marsh House. He operates strictly according to the dangerous marsh tides, possessing an intimate knowledge of the perilous local geography.

Esme is Arthur's wife during his later years at Monk's Piece. She enjoys the festive holiday season with her children, completely unaware that the traditional family activity of telling ghost stories causes her husband immense, silent distress.

Oliver is Esme's son and Arthur's stepson. During a Christmas Eve gathering, he eagerly initiates a session of telling frightening stories in the dark, an innocent holiday tradition that accidentally provokes Arthur's traumatic memories.

Will is one of Esme's sons who joins his brothers in sharing scary tales by the fireplace. He participates cheerfully in the family traditions, unaware of his stepfather's deep discomfort.

Edmund is another of Esme's sons. Along with his brothers, he takes turns recounting frightening folklore on Christmas Eve, which ultimately drives Arthur out of the room to write down his own real experience.

Spider is Mr. Daily's dog, loaned to Arthur for protection and companionship during his stay at Eel Marsh House. The dog provides Arthur with physical comfort and acts as an alert companion, reacting instinctively to unseen presences around the isolated property.

Nathaniel is the young son of Jennet Humfrye, legally adopted by Mrs. Drablow. His early childhood and custody are the focal points of the fraught letters Arthur discovers hidden inside the nursery of Eel Marsh House.