Mike Resnick lists some defining figures of different eras of 20th century English science fiction

Mostly familiar names, but I didn't know the chronological order in which they dominated the genre scene.

Actually, his post titled "The Sun Will Come Up Tomorrow" is a rant against naysayers of the genre. And the listing is only incidental - to make a point. But it was this listing (oldest figures first) that I found interesting:

1. Stanley G Weinbaum, Robert E Howard, H P Lovecraft
2. Robert A Heinlein, Isaac Asimov, Theodore Sturgeon, A E van Vogt, Leigh Brackett
3. Jack Vance, Ray Bradbury, Arthur C Clarke
4. Robert Sheckley, Alfred Bester, Cyril Kornbluth
5. Robert Silverberg, J G Ballard, Anne McCaffrey
6. Roger Zelazny, Larry Niven, Ursula K Le Guin