A dedicated and ambitious psychiatrist who takes on Sybil's complex case without payment and develops a close bond with her. She is committed to understanding and treating Sybil's multiple personalities.

Sybil's mother, who is portrayed as abusive and controlling, with her behavior heavily impacting Sybil's mental health. Her actions are influenced by her own troubled past and mental illness.

Sybil's father, characterized by his passivity and puritanical beliefs. His indifference and inaction contribute to Sybil's trauma and childhood experiences.

Sybil's grandmother, who provides a rare source of love and freedom in Sybil's early life. Her death marks a significant loss for young Sybil.

A domineering and religiously fervent man whose aggressive nature affects his family, including Sybil, who is unsettled by his beliefs.

Sybil's roommate and confidant, who is aware of her multiple personalities and assists her in managing them. Their relationship becomes strained over differing views on Dr. Wilbur's motives.

Sybil's childhood friend who maintains his friendship with her after a difficult period. His move away has a significant emotional impact on Sybil.