Annie Sullivan, the protagonist of William Gibson's The Miracle Worker, faces two main antagonists in the play--her own fears (fear of failure) and the Keller family, particularly Helen (her deaf and mute student) and Helen's father (Captain Arthur Keller). Both of her antagonists are, in essence, intertwined. She fears that she will fail at being successful as Helen's teacher. Being Helen's governess is Anie's first job. She is immediately met with extreme doubt that she will find any success at taming Helen's tantrums and teaching her to communicate. Since Helen's own family has failed, they doubt that Annie will succeed. 

Annie's strong will and pure determination allow her to face the challenges placed in front of her. Even with the doubt of those around her bearing down upon her, Annie refused to quit. She was able to face her antagonists and obstacles and find success with Helen. Based upon the themes defined by eNotes ("The Miracle Worker Themes"), "that the human spirit can triumph over even the most daunting of disabilities and that a dedicated teacher can transform the lives of those with whom he or she comes into contact," Annie was completely successful at facing her own personal conflicts and the doubts of others.