1. George and Myrtle Wilson: These characters embody the working class and represent the struggles of those who aspire to a better life. They are on the fringes of the wealthy world, and Myrtle is attracted to the allure of Tom Buchanan's wealth and status. George, while he is not explicitly poor, is struggling to make ends meet, and he is deeply affected by his wife's infidelity and death.
2. Nick Carraway: He is often considered a representative of the "middle class" in the novel. While he comes from a relatively wealthy background, he is not on the same level as the Buchanans or Tom's friends. He is a young man trying to make a living and achieve success in the world. Nick observes the wealthy, but ultimately finds their lifestyle shallow and ultimately destructive. He's also critical of their moral failings and the emptiness of their pursuits.
3. Catherine and Mr. McKee: These characters represent the "new money" crowd, who have made their fortunes through business and are trying to integrate themselves into the world of old money. They are characterized by their ambition and social climbing, but they are ultimately seen as shallow and lacking in genuine culture or sophistication.
4. The Valley of Ashes: While not a character itself, the Valley of Ashes represents the lower class, and those who are struggling to survive. This stark contrast to the lavish parties and extravagant lifestyles of West Egg is a constant reminder of the economic divide that exists in the novel.
5. Jordan Baker: Although a member of the wealthy elite, Jordan is often considered a bit of an outsider, especially within the group of "old money" characters. She is more independent and cynical than the others, and her pursuit of personal success and wealth sometimes clashes with the expectations of her social circle.
It's important to remember: The concept of "middle class" in the 1920s was different from what we understand today. The novel's focus on wealth and status makes it difficult to identify "middle class" in the traditional sense. But by examining the characters who are not part of the elite, struggling to survive, or trying to break into the upper echelon, we gain a better understanding of the social and economic realities of that era.