Walter is a young drawing master from a middle-class background living in London. He possesses a strong sense of justice and natural curiosity. After taking a teaching position at Limmeridge House, his social status creates complications when he develops romantic feelings for his pupil. He acts as the primary compiler of the various witness accounts that make up the narrative.

Laura is a wealthy young heiress who stands to inherit Limmeridge House. She is sweet, passive, and deeply bound by a promise made to her dying father to marry a man she does not love. Her vulnerability and substantial fortune make her the center of competing interests from the men around her. She strongly resembles the mysterious woman in white.

Anne is a distressed young woman who recently escaped from a private psychiatric hospital. She bears a striking physical resemblance to Laura and harbors an intense terror of Sir Percival Glyde. She wears white exclusively out of devotion to the late Mrs. Fairlie, who showed her kindness during her childhood.

Marian is Laura's devoted half-sister. Lacking wealth and traditional physical beauty, she compensates with sharp intelligence, bravery, and logical thinking. She is acutely aware of the limitations placed on women by society and is fiercely determined to protect Laura from harm. She records the unfolding events in detailed diary entries.

Sir Percival is a baronet from Hampshire who is engaged to Laura. Though outwardly charming and respectable to figures of authority, he shows flashes of a violent temper and a controlling nature. He faces significant financial difficulties and appears determined to secure Laura's fortune by any means necessary.

Count Fosco is an imposing, charismatic Italian nobleman who exerts a powerful influence over those around him. He considers morality to be culturally relative and takes great pride in his intellect. He travels with a collection of pet mice and birds that he has carefully trained, mirroring his approach to human relationships.

Madame Fosco is Laura's aunt who was disinherited by her family for marrying a foreigner. Once a vain and vocal advocate for women's rights, she is completely transformed by her marriage. She acts as a deeply submissive and obedient extension of her husband's will.

Frederick is the wealthy, reclusive master of Limmeridge House. He is an irritable hypochondriac who avoids unpleasantness or responsibility of any kind. He treats even minor disturbances as personal attacks on his fragile nerves and neglects his duties as a guardian to his nieces.

Gilmore is the practical, respectable family lawyer for the Fairlies. He views the world through a strict legal lens and expects upper-class gentlemen to behave honorably. He grows deeply uneasy about the aggressive financial terms Sir Percival demands for the marriage settlement.

Pesca is an energetic Italian expatriate teaching in London. He holds a deep, lifelong gratitude toward Walter for saving him from drowning. He enthusiastically repays this debt by securing Walter the teaching position at Limmeridge House.

Mrs. Catherick is Anne's mother, residing in Old Welmingham. She is a haughty, unsentimental woman who maintains a respectable facade in her community despite local gossip regarding her past. She shows little maternal warmth toward her daughter and is highly protective of her own reputation.

Mrs. Clements is an elderly, maternal woman who acts as a friend and guardian to Anne. She raised Anne for parts of her childhood and tries to protect her after her escape from the psychiatric hospital.

Mrs. Michelson is the earnest and respectable housekeeper at Blackwater Park. She is highly susceptible to Count Fosco's manipulative charm and struggles to interpret the disturbing events unfolding in the household.

Mr. Kyrle is a lawyer who takes over Mr. Gilmore's responsibilities when Gilmore falls ill. He approaches Laura and Marian's crisis with strict legal pragmatism. He requires concrete evidence over emotional appeals when considering their situation.

Mrs. Vesey is Laura's former governess who continues to live with the family as a companion. She provides a gentle, stable presence in Laura's life at Limmeridge.

Mrs. Rubelle is a foreign woman brought in specifically to nurse Marian through a severe illness. Her sudden presence at Blackwater Park is unnerving to the local staff and the attending doctor.

Mr. Dawson is a local doctor who tries to provide proper medical care for Marian during her illness. He finds himself constantly undermined and eventually driven away by Count Fosco's interference.

Fanny is Laura's loyal maid at Blackwater Park. She is unjustly dismissed by Sir Percival and subsequently becomes a crucial secret messenger for Marian's correspondence.

Jane is a woman sent by a doctor to prepare a body for burial. She completes her grim task at the Foscos' residence.