A six-and-a-half-year-old girl who is deaf and blind, known for her curiosity and strong will. She is a pivotal figure in the story as her learning journey with Annie Sullivan unfolds.

Helen's mother and the younger wife of Captain Keller, who remains hopeful about Annie's teaching efforts. She is supportive and plays a key role in bringing Annie into the family to help Helen.

Helen's father, a proud Southern newspaper publisher who often appears impatient but shows a compassionate side. He struggles with the challenges related to Helen's disabilities.

The indolent but evolving young man who is Captain Keller's son from his first marriage. Initially distant from Helen and Kate, he grows to reconcile with his family dynamics throughout the play.

Captain Keller’s sister and a regular presence at Ivy Green, known for advocating medical attention for Helen. She tends to indulge Helen.

A servant in the Keller household, who helps care for the family, particularly when Helen acts out. She is characterized by her tendency to spoil Helen with treats.

Annie Sullivan’s mentor from her time at the Perkins School for the Blind, who plays a foundational role in her backstory and motivates her to persist in her efforts with Helen.