Leiber was heavily influenced by H. P. Lovecraft and Robert Graves in the first two decades of his career. Beginning in the late 1950s, he was increasingly influenced by the works of Carl Jung, particularly by the concepts of the anima and the shadow. From the mid-1960s onwards, he began incorporating elements of Joseph Campbell's
The Hero with a Thousand Faces. These concepts are often openly mentioned in his stories, especially the anima, which becomes a method of exploring his fascination with but estrangement from the female.
Leiber liked cats, which feature prominently in many of his stories. Tigerishka, for example, is a cat-like alien who is sexually attractive to the human protagonist yet repelled by human customs in the novel
The Wanderer. Leiber's "Gummitch" stories feature a kitten with an I.Q. of 160, just waiting for his ritual cup of coffee so that he can become human, too.
His first stories were inspired by H. P. Lovecraft's Cthulhu Mythos and it seems that a letter of encouragement from Lovecraft during 1936 spurred his decision to pursue a literary career. Leiber later wrote several essays on Lovecraft such as "A Literary Copernicus" which formed key moments in the serious critical appreciation of Lovecraft's life and work.
Leiber's first professional sale was
Two Sought Adventure (
Unknown, August 1939), which introduced his most famous characters, Fafhrd and the Gray Mouser. His work as a writer earned much praise but little money, a problem exacerbated by bouts of alcoholism. In 1943 he sold his first novels - Conjure Wife to
Unknown and Gather, Darkness to
Astounding. From 1945-56 Leiber was associate editor of
Science Digest.
1947 marked the publication of his first book -
Night's Black Agents, a short story collection. Book publication of
Gather, Darkness followed in 1950. In 1951 Leiber was Guest of Honour at the World Science Fiction Convention in New Orleans. Further novels followed during the 1950s, and in 1958
The Big Time won the Hugo Award for Best Novel. Many further books were published in the 1960s. His novel
The Wanderer (1964) won the Hugo Award for Best Novel and he was awarded three further Hugos for Best Novella/Novellette: for "Gonna Roll the Bones" (1967),(which also won the Nebula Award in the same category); "Ship of Shadows" (1969) and "Ill Met in Lankhmar" (1970).
Our Lady of Darkness... originally serialized in short form in
The Magazine of Fantasy & Science Fiction under the title "The Pale Brown Thing" (1977) ... featured cities as the breeding grounds for new types of elementals called paramentals, summonable by the dark art of megapolisomancy, with such activities centering around the Transamerica Pyramid.
Our Lady of Darkness won the World Fantasy Award.
Leiber also did the 1966 novelization of the Clair Huffaker screenplay of
Tarzan and the Valley of Gold.
Many of Leiber's most-acclaimed works are short stories, especially in the horror genre. Owing to such stories as "The Girl With the Hungry Eyes" and "You're All Alone" (aka "The Sinful Ones"), he is widely regarded as one of the forerunners of the modern urban horror story. (Ramsey Campbell cites him as his single biggest influence. In his later years, Leiber returned to short story horror in such works as "Horrible Imaginings", "Black Has Its Charms" and the award-winning "The Button Moulder."
The short parallel world story "Catch That Zeppelin!" (1975) added yet another Nebula and Hugo award to his collection. This story shows a plausible alternate reality that is much better than our own, whereas the typical parallel universe story depicts a world that is much worse than our own. "Belsen Express" (1975) won him another World Fantasy Award. Both stories reflect Leiber's uneasy fascination with Nazism...an uneasiness compounded by his mixed feelings about his German ancestry and his philosophical pacifism during World War II.
Fans awarded him the Gandalf (Grand Master) award at the World Science Fiction Convention in 1975, he was Guest of Honor at the World Science Fiction Convention in Brighton, England (1979)and in 1981 the Science Fiction and Fantasy Writers of America voted him the recipient of their Grand Master award.
He was also a member of the Swordsmen and Sorcerers' Guild of America , a loose-knit group of Heroic Fantasy authors founded in the 1960s, some of whose works were anthologized in Lin Carter's
Flashing Swords! anthologies.
In an appreciation in the July 1969 "Special Fritz Leiber Issue" of
The Magazine of Fantasy & Science Fiction, Merril writes of Leiber's connection with his readers:
- That this kind of personal response...is shared by thousands of other readers, has been made clear on several occasions. The November 1959 issue of Fantastic, for instance: Leiber had just come out of one of his recurrent dry spells, and editor Cele Lalli bought up all his new material until there was enough [five stories] to fill an issue; the magazine came out with a big black headline across its cover ... Leiber Is Back!