In H. G. Wells’s The Time Machine, the underground creatures are called Morlocks. They live beneath the surface of far-future Earth, where they maintain machinery and emerge at night while the surface-dwelling Eloi live in apparent leisure.
The Time Traveller initially assumes that the delicate Eloi are the only descendants of humanity. He later discovers the Morlocks and realizes that the two groups may represent the long-term division of human society into privileged and laboring classes. The Morlocks’ underground existence reflects the harsh industrial world of work, while the Eloi embody a ruling class that has become dependent and physically weak.
The Morlocks are not Martians, and the Eloi are a separate future human species rather than another name for them. The Time Traveller is the novel’s protagonist, not a creature. Wells first published the story in 1895, helping establish ideas and imagery that became central to modern science fiction.