Neuromancer is a 1984 science fiction novel by American-Canadian author William Gibson. Set in a near-future dystopia, the narrative follows Case, a computer hacker enlisted into a crew by a powerful artificial intelligence and a traumatised former soldier to complete a high-stakes heist. It was Gibson's debut novel and, after its success, served as the first entry in the Sprawl trilogy, followed by Count Zero (1986) and Mona Lisa Overdrive (1988).

Gibson had primarily written countercultural short stories for science-fiction periodicals before Neuromancer. Influences on the novel include the detective stories of Raymond Chandler, the comic art of Jean Giraud, and William S. Burroughs's Naked Lunch (1959). Neuromancer expanded and popularised the setting and concepts of an earlier Gibson story, "Burning Chrome" (1981), which introduced cyberspace—a digital space traversable by humans—and "jacking in", a bio-mechanical method of interfacing with computers.

Neuromancer is a foundational work of early cyberpunk, although critics differ on whether the novel ignited the genre or if it was lifted by its inevitable rise. They agree it highlighted the genre's key features, like the placement of technological advancement against societal decay and criminality. Gibson's novel also defined the major conventions and terminology of the genre—cyberspace, jacking in, and Intrusion Countermeasure Electronics (ICE). Critics discuss the novel in the historical context of the 1970s and 1980s, a period marked by conservatism, deregulation, and free-market economics.

Neuromancer was released without significant hype but became an underground hit through word of mouth. Following release, it received critical acclaim and transformed the science-fiction genre. Mainstream recognition raised Gibson from relative obscurity. It remains the first and only novel to win all three of the Hugo Award, the Nebula Award for Best Novel, and the Philip K. Dick Award. It has been regarded as a classic work of the cyberpunk genre and, in 2005, was named one of Time's All-Time 100 Novels.

In 1981, William Gibson worked as a teaching assistant at his alma mater, the University of British Columbia. In the same year, his Nebula Award-nominated short story "Johnny Mnemonic" introduced one of Neuromancer's main characters, Molly. "Johnny Mnemonic" infused elements of crime fiction, like marginalised communities and criminal society, with technology, blurring the boundary of human and machine. The setting of the Sprawl and the concept of cyberspace first appeared in Omni the following year in his short story "Burning Chrome", and were popularised by Neuromancer. Later in 1981, Gibson was commissioned to write a novel by science-fiction editor Terry Carr for his second series of Ace Science Fiction Specials; he submitted an outline later that year with the working title Jacked In, eventually renaming it Neuromancer. Gibson did not understand computing or networking in much detail, primarily wanting the shared vocabulary surrounding the topics.

The novel underwent considerable revision, with Gibson saying he rewrote the first two-thirds twelve times to ensure there was both stylistic consistency and a "vaguely plausible" plot. Gibson's sought to eliminate "clunk", contracting his prose to ensure "individual parts carry more weight". He did not write the novel with a concrete outline, or initially know how it would end, writing the novel in "blind animal panic" because he thought it would fail if he did not hold the reader's attention. Gibson added the novel's final sentence ("He never saw Molly again.") to prevent himself from writing a sequel.

Neuromancer has many literary progenitors. Detective fiction, like the work of Raymond Chandler, is frequently cited as an influence on Neuromancer. For example, critics note similarities between Gibson's Case and Chandler's Philip Marlowe: Case is described as a "cowboy" and a "detective" and is involved in a heist; Molly, the novel's primary female character, has connections to the "molls" of 1940s film noir. Case's illegal practices, like theft and murder, situate him within a wider tradition of transgressive detectives, like the opiate addiction of Arthur Conan Doyle's Sherlock Holmes. Gibson stated that the pulp noir core of the novel was key to engaging his readers, and cited the works of Dashiell Hammett and Robert Stone as major influences on its style. For dialogue, the author incorporated late 1960s Toronto drug dealer and biker slang into the novel. Gibson imagined the novel's time frame as the 2030s but purposefully omitted explicit dates; he said the novel, and its sequels, were written to reflect the 1980s.

Gibson's prose style—fast-paced, fragmented imagery—resembles the styles of William S. Burroughs and J. G. Ballard. Burroughs's Naked Lunch (1959) is frequently cited by critics as an influence on Neuromancer, including by one as its "principal source", as a literary predecessor of Gibson's "cyberspace". Gibson's conception of cyberspace was compared by Samuel R. Delany to Roger Zelazny's early short stories; Delany and other critics have explored the character of Molly as a development on the cyborg assassin of Joanna Russ's The Female Man (1975).