From Fan History Wiki
Fan art, also spelled fanart, is artwork created by a fan. It is based on characters or universes from television, movies, video games, anime, cartoons, comics, etc.
- fanart: artwork based on either a) canon, or b) fanon. Fanartists are highly sought after in the HP fandom and many fanfiction authors proudly display the fanart that has been created for their fics. HP fanartists, and all bookcentric fanartists, have the advantage of having no one face for any of the characters; while Tom Felton plays Draco Malfoy in the HP films, most fanart does not depict Tom Felton. Fanartists are at liberty to draw characters however they see fit. 
Fan art was popular and highly in demand on the rapidly growing fanzine market in media fandom during this decade. Publishers of zines would seek out quality work to illustrate their included stories, provide "filler", decorate 'zine covers, etc. Because of printing limitations in this "era before the Xerox machine", pen-and-ink/line art was quite popular as it was easier to reproduce. Some artists who produced more delicate pencil, shaded artwork would only work with certain fanzine publishers who they trusted to put the extra effort (and cost) into reproducing their artwork properly. Color artwork (of generally 2-3 colors), had to be separated and printed one color at a time, greatly increasing the cost of that page being printed.
By the late 1970s, media conventions were holding art shows where artwork could be purchased, either for private collecting or fanzine publishing rights. The common practice, however, of fan artists being able to receive monetary payment for their works while fan writers couldn't, did make some fans upset and remains an issue of contention today.
DeviantART includes artists that do fanart but in total it is an art community. It was created "August 7, 2000 by Scott Jarkoff, Matthew Stephens and Angelo Sotira, amongst others."  It became hugely influential in the fanart community despite some historical antagonism against fanart.
MediaMiner.org is a fanfiction and fanart archive founded in 2001. It became one of the larger homes for anime based fan art.
In media fandom, by the 2000s illustrative fan art had become somewhat of a dying art as fanzines had become replaced largely by the internet for sharing fiction. While some fandoms such as Kirk/Spock, Starsky & Hutch, The Sentinel and Lord of the Rings continued to be fertile grounds for fan artists to work as fanzine producton continued, it was much less popular than it used to be. Photo-manipulation became increasingly popular, as fans were more concerned about having the exact likeness of their favorite characters than a hand-drawn or painted work of art.
This section needs more information.