Buddy Willard: Esther’s college boyfriend, a medical student who represents conventional expectations of marriage and domesticity. He’s well-meaning but insensitive, and Esther grows disillusioned with him, especially after learning he’s not as pure as he seems (he had an affair).

Doreen: A fellow intern at the magazine, bold and rebellious, with a Southern drawl and a sharp wit. She’s a foil to Esther’s more reserved nature and introduces her to a freer, less inhibited lifestyle, though they drift apart as Esther’s mental state worsens.

Joan Gilling: A former acquaintance from college who later becomes a patient at the same psychiatric facility as Esther. Joan is a complex figure—athletic, seemingly confident, and possibly in love with Esther—whose suicide attempt and eventual death haunt the narrative.

Mrs. Greenwood: Esther’s mother, a practical but emotionally distant widow who struggles to understand her daughter’s illness. She pushes Esther toward normalcy (like shorthand lessons) but lacks the tools to truly support her.

Doctor Nolan: Esther’s psychiatrist at the private hospital, a compassionate and unconventional woman who helps Esther through electroshock therapy and recovery. She’s a rare positive authority figure, offering understanding rather than judgment.

Jay Cee: The editor at the fashion magazine where Esther interns. She’s stern but fair, recognizing Esther’s talent and pushing her to excel, though Esther feels inadequate under her gaze.

Marco: A Peruvian man Esther meets at a party, charming yet sinister. He attempts to assault her, embodying the predatory side of the male attention Esther encounters.

Constantin: A translator Esther goes on a date with in New York. He’s polite and intellectual, but their interaction leaves Esther feeling detached, reflecting her growing alienation.

Philomena Guinea: A wealthy novelist and Esther’s benefactor, who funds her scholarship and later her hospital stay. She’s based loosely on Plath’s real-life patron, Olive Higgins Prouty.