The terms "Eloi" and "Morlocks" were introduced in what 1895 H.G. Wells novella to describe the two divergent branches of future humanity?

The Time Machine

The novella is a foundational work of science fiction that popularized the concept of vehicle-based time travel. It uses the two species to satirize the Victorian class system, with the Morlocks representing the working class and the Eloi representing the leisure class.