At first, science fiction stories were ephemeral. They appeared for a month in a pulp magazine, then were never seen again. Until the 50s, novels were few and far between, and were often "fix-ups" -- a group of previously published short stories set in the same universe (e.g., The Foundation Trilogy, The Martian Chronicles). It's quite possible these works and authors would have just been forgotten if it weren't for Groff Conklin.
Conklin was not an author nor was he a magazine editor. He was an anthologist. From 1949 until his death in 1968, he gathered together the best of the magazine SF stories into over 40 anthologies that helped define the genre.
This was essential. I started reading SF in the early 60s, and didn't know about the pulps. By that time, only a few were being published* and I didn't know what to look for at the newstands, especially since the era of pulp fiction had ended. But I did haunt the bookstores and my school library, and the name Groff Conklin was everywhere. You really couldn't look at a bookshelf without seeing a collection with his name on it.
Conklin knew the great stories. He was fond of authors like Theodore Sturgeon, Isaac Asimov, Robert Heinlein, Damon Knight, William Tenn, Arthur C. Clarke, Cordwainer Smith, and all the greats of the genre. His books were the way to get a grounding in science fiction.
My favorite of his anthologies was something called Science Fiction Oddities, which includes such gems as Alan Arkin's "People Soup,"** Isaac Asmov's "What is This Thing Called Love?,"*** R.A. Lafferty's amazing "What Was the Name of That Town?," Charles Harness's "The Chessplayers," Fritz Lieber's Rump-Titty-Titty-Tum-TAH-Tee," and several others. All were off-beat stories that went into areas that few dared go and brought more smiles of pleasure than any other collection I have read.
Conklin continued to collect and publish anthologies until his death. He was purely a labor of love: the economics of such a book are pretty dismal even in the best of times. He paid the authors low rates (not a big problem, since they had already been paid for the original publication), and didn't have a lot left over for him. I doubt the books were his main source of income.
Of course, not only is Conklin forgotten, but the reprint SF anthology has gone the way of the passenger pigeon. People far prefer novels these days, and if they want a reprint anthology, it'll be from a single author they've discovered through books. That's too bad. The real advantage of a reprint anthology was that it had great stories by authors you never saw before. If someone impressed you, you could look for more of his work. Now, with the exception of some anthologies edited by Martin H. Greenberg, it's much harder to have that sort of smorgasbord of authors to sample.**** But, alas, it's far too late to change that trend.
Conklin's anthologies are long out of print, and are unlikely to be reprinted due to issues of getting the rights.***** It's a loss to the field, especially since the stories may be forgotten.
* Fantasy and Science Fiction, Analog, Amazing, Fantastic and one or two others.
**Made into a short film that was Adam Arkin's film debut.
***Asimov's preferred title, though I like the original one: "Playboy and the Slime God."
****Martin H. Greenberg has stepped into Conklin's footsteps, with original and reprint anthologies. He often works with other authors -- a big name to make the selection of stories, and, for reprints, someone to find stories for the anthologies (Charles G. Waugh had a self-made index of SF stories by theme and did a lot of the digging up of obscure works. Greenberg actually just handled the business end in all these, getting the rights and selling the concept.
****It would take a Herculean effort to track down the authors and their estates. The only one that seems to be available is one he co-edited with Isaac Asimov, which is around because of Asimov's name.