In the 1960s, Harrison began the novel series through which he is probably best remembered. The Stainless Steel Rat books focused on the thief/smuggler Slippery Jim DiGriz, the Deathworld books on culture and environmental clashes on the backdrop of a difficult-to-colonize planet, the Bill The Galactic Hero book offered up direct parodies of bad science fiction. Like many of the most popular and well-liked genre authors of the 20th Century, Harrison's work was generally smart but offered multiple entrance points for readers of various ages. They are frequently cited by current writers and fans of science fiction and fantasy as influential books from early on in their discovery of that kind of writing.
His 1966 novel Make Room! Make Room! was the basis for the 1973 science fiction movie Soylent Green, and contains potent elements of social criticism only a few of which made it into the film version. It was dedicated to Harrison's then-young children, which gives poignancy to the novel's strong foreboding nature. In the 1970s, Harrison and the author Brian Aldiss worked as anthology series co-editors and were among the leaders in that corner of publishing in terms of collecting valuable material from decades past.
Like several authors of his generation, Harrison used the relative freedom of being a writer (no doubt in close conjunction that living costs be kept relatively low in an uncertain profession) to live in various places around the world. He would reside at various times in Denmark, England, Ireland, Italy and Mexico. For a time he taught a science fiction course at San Diego State University and organized similar courses in university summer programs. He continued his involvement in various fan- and professional-driven science fiction organization and was a presence at a lot of the early conventions.
Three 12-episode adaptation of Stainless Steel Rat stories appeared in 2000 AD in the late '70s to early '80s. "The Stainless Steel Rat" ran in #s 140-151 (1979/80), "The Stainless Steel Rat Saves The World" ran in #s 166-177 (1980) and "The Stainless Steel Rat For President" appeared in #s 393-404 (1984/85). Some of this material appeared in 1985 from Eagle Comics under its own cover.
In 2009, Harrison won the Damon Knight Memorial Grand Master Award from the Science Fiction and Fantasy Writers of America. He was involved in advocacy for Esperanto; the language appears in some of his novels. He won a Nebula Award for Best Script and was nominated for multiple Locus Awards.
A last major piece of writing was released two years ago -- another Stainless Steel Rat book -- and Harrison claimed to be working on a secret project.
I grew up with Slippery Jim's exploits across the stars as a kid and discovered Bill the Space Trooper (who keeps getting parts from people he's not too fond of) in high school, and from there branched out into space, cyberpunk and military sci-fi writers like Heinlein, John Scalzi, Simon Green, David Weber, and William Gibson, but it was Harry Harrison's Vietnam "war is hell" metaphors that really made the genre interesting, thought-provoking and darkly funny to a young, snarky Zandar. Even through Stainless Steel Rat's adventures are 50 years old, they remained as relevant to the world now as they did then and are definitely worth the read. He's the first atheist hero I can recall reading about, too.
I hope Harrison's project sees the light of day. Make that happen, universe.