* Boo Radley: He's a recluse who lives in a dilapidated house and is the subject of many rumors and superstitions. He's feared and ostracized by the community due to his mysterious past and his avoidance of social interaction.
* Tom Robinson: He's a black man falsely accused of raping a white woman. He's a victim of racism and prejudice, and his trial highlights the deep societal divisions and injustices that exist in Maycomb.
While other characters experience social isolation or prejudice (like Scout and Jem for their curiosity, or the black community in general), Boo and Tom are the most clearly defined as outcasts due to their direct experience of fear, misunderstanding, and discrimination.