A fanzine (see also: zine) is a nonprofessional and nonofficial publication produced by fans of a particular cultural phenomenon (such as a literary or musical genre) for the pleasure of others who share their interest. The term was coined in an October 1940 science fiction fanzine by Russ Chauvenet and first popularized within science fiction fandom, from whom it was adopted by others.

Typically, publishers, editors and contributors of articles or illustrations to fanzines receive no financial compensation. Fanzines are traditionally circulated free of charge, or for a nominal cost to defray postage or production expenses. Copies are often offered in exchange for similar publications, or for contributions of art, articles, or letters of comment (LoCs), which are then published.

A few fanzines have evolved into professional publications (sometimes known as "prozines"), and many professional writers were first published in fanzines; some continue to contribute to them after establishing a professional reputation. The term fanzine is sometimes confused with "fan magazine", but the latter term most often refers to commercially-produced publications.