In the novel "To Kill a Mockingbird" by Harper Lee, the character Tom Robinson, who is a black man can be identified as a "mockingbird" because he is falsely accused of raping a white woman — a crime for which he is shot to death. In the context of the novel, a mockingbird is a symbol of innocence, especially when destroyed by evil.
In addition to being at a racial disadvantage in the prejudiced community of Maycomb, Tom Robinson is also physically handicapped. He has been likened to a bird with a broken wing.
He is one of a number of characters in the novel who can be viewed as "mockingbirds," positioned alongside Jem, Dill, Mr. Raymond and Boo Radley. In fact, Tom Robinson is directly juxtaposed with the character of Boo Radley by virtue of them both being handicapped, although Boo Radley is white. Whereas Tom Robinson's "mockingbird" status comes towards the end of his life, however, Boo Radley's is rooted in his childhood at the hands of his abusive father.
The main character, Scout, says that hurting Boo Radley would be like "shootin' a mockingbird." Meanwhile, a quote that identifies Tom Robinson as a mockingbird comes from Mr. Underwood, who remarks after Tom's execution that it was like "the senseless slaughter of songbirds."