Answer: William Gibson

Although now ubiquitous in usage, the term cyberspace–used to denote both the social and physical networks that make up the Internet as a unique space distinct from non-networked world–didn’t enter in the English lexicon until 1982. The term was coined by Sci-Fi writer William Gibson in his 1982 short story “Burning Chrome” but was ultimately launched into popular usage by his 1984 novel Neuromancer:

Cyberspace. A consensual hallucination experienced daily by billions of legitimate operators, in every nation, by children being taught mathematical concepts… A graphic representation of data abstracted from the banks of every computer in the human system. Unthinkable complexity. Lines of light ranged in the nonspace of the mind, clusters and constellations of data. Like city lights, receding.

While first widely used by fans of the novel and early internet users, it was quickly adopted by the media as a catch-all term to encompass everything going on in the new and seemingly uncharted arenas of online interaction and global networking.