Is there anyway to get the guy who originally made it to transfer ownership to you? I did that with all official images I "commissioned" on my site.
For instance, my banner was made by someone else and I got them to state in writing that it belonged to TheDarkTower.com
My wiki image is fan art, and it belongs to someone else, if he wanted me to stop using it and give it to someone else, totally acceptable. Since he wouldn't sign it over to me, I have to deal with that eventuality.
banner is
here
wiki is
here