Rather than stereotypes, it is useful to view the characters in Tom Sawyer as types. The difference? Many of the characters in the novel can be summed up as stereotypical, but Twain brings them to so much life that they seem to live, rather than just being the shallow things that stereotyped characters usually are. That said, Injun Joe is a stereotype of period prejudice. Mary, Aunt Polly's daughter, is mostly gender stereotypes. Becky Thatcher is more than just a stereotype, but her appearance is that of standard female beauty. Joe Harper is a standard period adventurer, and the Model Boy is explicitly held up as a type of proper behavior for boys.