Can you copyright fan art? If you took a TV show graphic and edited it, added graphics to it on photoshop, would you gain partial copyrights to it?
Taking the original or portion of the TV Show graphic would be copyright infringement - even though you edited it. You have an automatic copyright on any 100% original works you create.
Fair use has a lot of grey areas and relying on it, especially for a commercial site (generates any revenue) can invite costly legal problems. In any event, it wouldn't be able to be copyrighted. http://en.wikipedia.org/wiki/Fair_use
Just to add to what mjewel said, what you are proposing is making a derivative work. Here is what the U.S. Copyright office has to say: http://www.copyright.gov/circs/circ1.html#wci The new bits of a derivative work can be copyrighted, but only the copyright holder can authorize the creation of such a work. http://www.copyright.gov/circs/circ14.html
I have a friend wich build a fan game based on World of warcraft. He spoke with blizzard a few times and then they let him use all images and such So speak with the company that is the owner of the art. Thats the most safest