Overview
Fan art (ファンアート, fan'āto) is a generic term for derivative works in English-speaking countries that refers to illustrations depicting characters from existing manga, anime, and video games, as well as works that add their own settings and adaptations to these works.
In English-speaking areas, works of fiction are often referred to as fan fiction and illustrations as fan art.
External Links
English
Japanese
ファンアートとは [単語記事] - ニコニコ大百科 (NicoNico Encyclopedia)