A fan convention is an event in which fans of a particular topic gather to participate and hold programs and other events, and to meet experts, famous personalities, and each other. Some also incorporate commercial activity. The term dates back to at least 1942.

Science fiction conventions are gatherings of fans of the speculative fiction genre, science fiction. Historically, science fiction conventions had focused primarily on literature, but the purview of many extends to such other avenues of expression as films, television, comics, animation, and games. The format can vary but will tend to have a few similar features such as a guest of honour, discussion panels, readings and large special events such as opening/closing ceremonies and some form of party or entertainment. Science fiction conventions started off primarily in the UK and US but have now spread further and several countries have their own individual conventions as well as playing host to rotating international conventions.