The Good Doctor's 1955 novel about time travel does things a little differently. He postulates a reality outside normal Time, called Eternity. In Eternity, bouncing back and forth between centuries (in vehicles called Kettles) is easier than traveling Interstate 95 between Florida and Maine in your Camry. Eternity is (naturally enough) populated by Eternals, a priesthood of technicians, calculators, and observers who watch over Time. Their self-appointed task is to monitor Time, and make slight butterfly-effect Changes at critical points to alter subsequent events for the "better."
(Did you ever see that Jean-Claude Van Damme movie, Timecop? It's kinda like that, except much more talking, much less violence, and much more imagination. Come to think of it, it's not much like Timecop.)
All is well and good with Eternity, until one minor Eternal, Andrew Harlan, falls in love with a young lady from Time named Noÿs. (Yes, a y-umlaut). Harlan discovers that one little planned Change will have the effect of deleting Noÿs from reality. He decides that he can't let that happen, even if he has to bring about—drumroll, please—the End of Eternity!
A pretty good yarn from Asimov. As often happens, the Asimovian protagonist must wade through a lot of circumstances that aren't as they initially seem, and deal with a number of people whose motives are mysterious. Downside: the workings of Eternity require piles of tedious explication, usually accomplished by wooden dialogue. "As you know, Harlan, …"