Originators And Successors

Mark Twain, pre-Wells, did not have access to the phrase, "time travel," so I searched A Connecticut Yankee In King Arthur's Court for his terminology and found that the phrase that he used was "transposition of epochs."

(Mark Twain and William Shakespeare are characters in Neil Gaiman's The Sandman. All imaginative literature connects.)

HG Wells wrote about the Time Traveller, the Time Machine and "time travelling." His successors write about time travellers, time machines and time travel.

Robert Heinlein wrote the Future History. His successors write future histories.

Poul Anderson perfected time travel and future histories. 

"Perfected" is a value term. James Blish thought that:

no one had written any good time travel fiction yet;

Heinlein's circular causality stories were quite limited applications of the concept;

it would be possible to base a novel on a finite spinning universe theory that allows for time travel;

(I think that) all the characters would be built up from one character.

But Blish never wrote it.