•Why it earns a slot
The Time Machine is the founding text of far-future speculation in English fiction, introducing both the mechanical time-travel device and the idea that social class stratification, taken to its logical extreme, could biologically split the human species.
An unnamed Victorian inventor travels to the year 802,701 and discovers that humanity has split into two degenerate species: the frail, passive Eloi who live on the surface and the pale, subterranean Morlocks who tend machinery and prey on the Eloi at night. After losing his machine, surviving a forest fire in which his Eloi companion Weena perishes, and glimpsing a dying Earth tens of millions of years in the future, the Time Traveller recovers his machine and returns home, only to depart again and never come back.
This distillation is written from the freely available original, which is always the better read when you have the time: gutenberg.org.