Stock characters draw from widely known cultural types for their characteristics and mannerisms, and are often used in parody. Every culture has its own set of stock characters. In Italian commedia dell'arte, for example, Scaramouche epitomized the unscrupulous and unreliable servant. In modern American culture, Thurber's Walter Mitty created the mold for the hen-pecked husband and dreamer.
Writers should be aware that racially based stock characters present a number of risks unless the writer is intimately familiar with the culture. It's easy to get the details wrong, and incorrect stereotypes may offend the reader. Either way, the reader is taken out of the fictional dream and left in doubt of the writer's authority.