Two weeks ago, one of the great classic writers of science fiction passed away: Jack Williamson. His famously long career spanned from the Gernsbackian beginnings of the modern genre in 1928 to a final novel, The Stonehenge Gate, published in 2005, and was already a nonagenarian when I started reading him in the late 1990s.
I've enjoyed a great deal of his science fiction, which is always marked by a sense of adventure and imagination. The early The Green Girl sends its heroes beneath the sea in a Verne-inspired "omnimobile". The Legion of Space and its sequel The Cometeers were some of the most entertaining of the early "space operas". The dystopian "With Folded Hands" and the subsequent The Humanoids contain a famous treatment of robots which was influential on both the field and actual AI researchers like Marvin Minsky. Hal Clement thought that The Legion of Time was "the best time travel story ever written"; not only was its treatment of alternate timelines one of the earlier ones, but the specific "war fought by time traveling soldiers from different eras" premise was taken in a very different direction by Fritz Leiber in The Big Time and related stories about the "Change War". While he was one of the first science fiction writers to treat the theme of cloning (he mentions his 1954 "Guinivere for Everybody" as being one of the earliest examples), he did a little cloning himself: in 2001, I submitted Iskandar from his 1934 Weird Tales science fantasy "The Wizard of Life" to the "clones of Fu Manchu" listing of characters inspired by the famous villain on Lawrence Knapp's definitive Fu Manchu website. His stories also inspired some memorable art, like the February 1939 Astouding Science Fiction cover that marked the debut of that magazine's frequent cover artist Hubert Rogers. And his influence also appears in nonfiction: Carl Sagan devotes a good portion of the chapter "Remaking the Planets" in Pale Blue Dot to a discussion of Williamson's 1942 tale "Collision Orbit" (which I haven't read, but which is available as part of the book Seetee Ship), as an early attempt to deal realistically with asteroid colonization and antimatter (the rhodomagnetic robots of "With Folded Hands" and The Humanoids also get a mention in Broca's Brain).
In addition to frequent appearances in multi-author anthologies (Isaac Asimov includes two Williamson tales in his anthology of personal favorites Before the Golden Age), del Rey's 1970s The Best of Jack Williamson has a nice selection of his stories, and for the fan who's devoted to truly digging in to Williamson's work, Haffner Press has a comprehensive series of collections aiming to cover his complete short stories and many of the shorter novels; five volumes have been published so far, covering Williamson's work up to mid-1940. Fittingly, the first volume, The Metal Man and Others (1999), has an introduction by another of the grand old-timers, Hal Clement — whose classic short story "Proof", about intelligent creatures from the Sun, was published in 1942; and whose final novel about a water world, Noise, came out in 2003 (I was lucky enough to see him at Readercon 14 the previous year, where he read from the then-forthcoming novel).
(via bOING bOING, which coincidentally also mentioned his late novel Terraforming Earth two months ago.)