Harlan EllisonI have no hesitation in ranking him with Poe and Kafka and Borges and Collier and Blackwood and Machen and Shirley Jackson and Gerald Kersh and Rampo and Stanley Ellin; than whom there are no greater.
Fritz Leiber Jr. was a prolific and highly admired writer of speculative fiction from the 1940s to his death in 1992. He started his career in the golden age of pulp magazines with tales in Astounding Stories, Thrilling Mystery, Unknown, and Weird Tales. His first story collection, Night's Black Agents was published by Arkham House in 1947. Starting in 1962 with Shadows with Eyes, his popularity was such that collections of his short stories would appear regularly until 1984. Interspersed with these collections were ten novels and a novelization of a Tarzan movie.
Leiber wrote Science Fiction, Fantasy, and Horror, and often blended them together. According to the author, “all I ever try to write is a good story with a good measure of strangeness in it.”  His feelings about genre distinctions, however, are even stronger. In an interview with Paul Walker, he said that “only second-and-third rate writers consider sf, supernatural horror, sword-and-sorcery, etc. as genres—word games to be played in idle moments at half-speed creativity and care.”
Leiber's writing career may have started in the Pulp Age but it in no way ended there. It extended into the New Wave and beyond. Norman Spinrad has pointed out that Leiber “although perhaps never generally considered the single most important science fiction writer in any of these periods, Leiber has been regarded as one of the most significant writers in all of them.”
Leiber has been described by peers as a “writer's writer.” p. 5 He was the writer that other writers read. His admirers include and have included Stephen King, Ramsey Campbell, Neil Gaiman, Poul Anderson, Harlan Ellison, and Terry Pratchet to name a few. One reason for the admiration was that he continuously honed his craft. Editor and critic, Malcolm Edwards, has described Leiber as being “the only sf and fantasy writer of his generation still developing and producing his best work” Stephen King has said that Leiber “continued to be an innovator, influencing the course of the horror genre well after the field had become a supermarket and chain bookstore mainstay.”
Most of Leiber's oeuvre was in the short form. He was a master of the short story. Nevertheless, he did write a handful of novels, a few of which were of serious consequence. Additionally, he published essays and reviews, and was an editor for Science Digest for a decade as well as a staff contributor to an encyclopedia.
Some themes were favorites of Leiber. Among these were cats, chess, the irrational versus the rational, sex, cold war fears, theater, Jung's Anima, and literature. Of the last on this list, literary references pervade his works p. 6 According to Byfield, “Leiber hopes for readers who share his diverse reading tastes.” p. 6 Byfield further cautions, as such, “unless [readers] meet the demand, they miss half of Leiber's allusions and experiments, finding little more than casual enjoyment.” p. 6 And yet, contrary to Byfield's warnings, Leiber was highly popular, winning six Hugo awards, which are voted upon by readers, and had four speculative fiction magazines dedicate an entire issue to him. p. 5