What term describes characters that do not undergo any significant change throughout a story?

The term that describes characters who do not undergo any significant change throughout a story is "static." Static characters remain largely the same in terms of personality, beliefs, and overall development from the beginning of the story to the end. They often serve specific functions in the narrative, such as providing contrast to dynamic characters who do evolve or transform.

The concept of static characters is important in literary analysis because it allows readers to explore how certain characters contribute to the themes and conflicts of the story without personal growth or change. In contrast, dynamic characters experience significant internal or external development, which is not the case for static characters.

Other terms listed, such as three-dimensional or two-dimensional, refer to the complexity and depth of characters. Three-dimensional characters are well-developed with complex personalities, while two-dimensional characters are more flat or simplistic, but both still can undergo changes. However, static characters, as defined, lack this progression, making "static" the correct choice for this question.