The novel's villain. Injun Joe is an anti-social adult, motivated by revenge and ruthless in exacting it. He brings both realism and romanticism to the novel. On the one hand his behavior forces Tom and his friends to confront injustice and criminality. On the other his fantastic escapes and discovery of treasure serve as plot devices that move the novel along as a page-turning adventure story. He is also half Native American, and has faced discrimination in society as a result. Even so, Twain's depiction of him is unsympathetic.