Boo Radley was just a teenager when his joy and freedom was ripped away from him. When he was just a little kid he got mad at his father and stabbed him in his leg. Ever since then he had been locked away in his house and no one has seen him since. Throughout the book Jem and Scout were trying to find a way to get Boo Radley out of his house. At the end of the book Bob Ewell is chasing Jem and Scout through the street when Boo Radley comes and saves them from what was about to be a life threatening situation.
Another example of a person that just wanted to bring good to the world was Mayella Ewell. Mayella Ewells innocence was ripped away from her when her father made her frame a man for a crime that he didn't commit. All Mayella ever did was help raise her seven siblings and take care of the roses in her garden. The mockingbird that was inside died because of somebody else's actions.
Tom Robinson a man who was just willing to help a young girl with no one by her side was actually shot 17 times and killed. Tom was falsely accused of rape by Bob Ewell and Mayella Ewell (the victim of the rape). Tom Robinson's hope was lost when he tried to escape from jail to tell his family that he would never see them again.
Every person in her book that was a true mockingbird died and something died with them. A symbolic mockingbird is a person who brings good to the world.