Auggie's protective older sister who feels overshadowed by the attention Auggie requires. She seeks her own identity, eventually wanting to be known as Olivia. Via embraces her independence during high school and reconciles with her family.

Auggie's loving parents, Isabel and Nate, who dedicate themselves to meeting his needs. Isabel left her career as a children's book illustrator to care for Auggie, while Nate provides humor and support. They initially debate sending Auggie to school but ultimately support his social development.

The Pullmans' beloved pet and an emblem of unconditional love. Her presence is comforting to Auggie and the family until her death, which forces them to adapt and embrace new beginnings.

Auggie's first true friend at Beecher Prep, who sits with him at lunch when no one else will. She values Auggie's sense of wonder and despises how others treat him rudely due to his appearance.

A student assigned to be Auggie's welcome buddy. Although initially hesitant and influenced by peer pressure, Jack grows to be one of Auggie's loyal friends, standing by him against bullies.

A student who pretends to befriend Auggie but is ultimately rude and bullying towards him. His actions and attitudes isolate him from other peers by the end.

The principal of Beecher Prep who supports Auggie's right to attend school and encourages his integration. Mr. Tushman recognizes Auggie's kindness and courage.

A fellow student and welcome buddy at Beecher Prep who is academically driven and involved in theater. She is friendly towards Auggie but not as actively supportive as Jack and Summer.