Tom Robinson displays empathy at his own trial while on the witness stand when he confesses that he felt sorry for Mayella Ewell, whom he is accused of raping. Mayella is the lonely, abused daughter of Bob Ewell in the story. Another example of empathy at the trial is when Atticus Finch's children, Scout and Jem, sit in what's called in the book the "colored section" of the court house to show their support for Tom Robinson and the African-American community.
The overall character of Atticus Finch is an example of how empathy is used in the novel. He displays empathy in his strong beliefs of racial equality, which was uncommon in the 1930s in Alabama. He demonstrates this further by agreeing to defend an African-American man, Tom Robinson, in court on charges of rape despite public criticism.
Arthur "Boo" Radley is a character in the novel who didn't leave his home for a period of three years. Because of this, he was often subject to teasing from children. Children would also sneak up to the Radley home's windows and peek through to try to catch a glimpse of him. Scout begins to feel guilty about the way she and some of the other neighborhood children treated Boo and remarks at the end, "you never really know a man until you stand in his shoes and walk around in them," an expression of true empathy.