The 10 most commonly used works for fan fiction on fanfiction.net

Harry Potter
Lord of the Rings
Gundam
Yu-Gi-Oh
Final Fantasy
Dragon Ball Z
Buffy: The Vampire Slayer
Digimon
Naruto
Sailor Moon

Please notice there are two fantasy works at the top of the list, seven manga, and one fantasy-horror tv-series.
Did you know that 9 out of 10 fanwriters are in fact women?