What is the name of Holden Caulfield's younger sister?

Holden Caulfield’s younger sister is Phoebe Caulfield.

Phoebe is one of the most important people in Holden’s life and the member of his family with whom he feels the strongest emotional connection. Although she is younger than Holden, she is perceptive, direct, and willing to challenge his complaints about school, adults, and “phoniness.” Her intelligence and emotional clarity often contrast with Holden’s confusion and impulsiveness.

When Holden visits his family’s apartment, Phoebe quickly realizes that he has been expelled and presses him to explain what he cares about. During their conversation, he describes his fantasy of being “the catcher in the rye,” protecting children from falling off a cliff. Phoebe recognizes that Holden has misunderstood the Robert Burns poem inspiring the fantasy, an exchange that reveals both his longing to preserve innocence and his difficulty understanding adulthood.

Phoebe later meets Holden at the Metropolitan Museum of Art and the Central Park Zoo. Their reconciliation at the carousel gives the novel one of its most hopeful scenes. Sunny, Jane Gallagher, and Sally Hayes are separate characters, not Holden’s sister.