In "Huckleberry Finn", a stereotyped character is Huck's slave friend, Jim. Jim, a slave who Huck helps escape, is not a particularly dynamic or detailed character. Not that stereotypes are a good thing or anything, but Jim basically just acts like you would expect a typical slave of the period to act. It seems that Mark Twain just needed a friend to accompany Huck on his interesting and wacky Mississippi River adventures, and a slave seemed a good choice, because it would emphasize Huck's lack of racism, or lack of overall views and opinions like those of the general populace at the time.

By just adding in a stereotyped slave character, Twain not only subtly brings up a major issue of social conflict at the time, but also provides his main character Huck with a good friend to relate with and escape with. For what the author had in mind, a simple stereotyped character worked out perfectly. Jim's character didn't detract attention or focus from what the author was trying to say, or distract readers with boring exposition on his personality. Using stereotyped characters in stories has the advantage that exposition is not really necessary; most readers will already have a pretty good mental picture of how this type of person would act, talk, etc.