1. Atticus. Atticus is a symbol for justice and equality. Judge Taylor did choose him to represent Tom Robinson, but in reality Atticus is the best man in Maycomb for the job. He believes that all men are equal, regardless of their skin color. He also believes that he must try to prove Tom’s innocence, even though he knows the court case will be lost.
2. Boo Radley. Boo is a symbol of childlike innocence and loyalty. With rumors running rampant in Maycomb about Boo, he continues to stay inside his home UNTIL Scout and Jem (he views Scout and Jem as “his own”) need him. He is fiercely loyal to the children and when their lives are threatened, he comes out to save them and kill Bob Ewell. After such an act of heroism, Boo quietly stands in the corner of Jem’s room and awaits for the sheriff to dish out his charge. Like a child, Boo is innocent the way the world works. He almost seems horrified by his actions. The sheriff lets him go though, and allows everyone to think Bob Ewell fell on his own knife.
3. In Chapter 10, the rabid dog is a symbol of racism. The dog is not actually doing anything wrong rather than walking down the street with the assumption that he has rabies. Like Tom Robinson, the dog was not actively harming anyone. However, the town knew that the dog must be put down just like Tom must be charged “guilty” in the eyes of the town. Atticus is the only one willing to stand up and shoot the dog, just like he is the only one brave enough to defend Tom Robinson.
Hope that helps!