Hmm. I seriously doubt that desktopexchange.com, the site Jafo linked to, has any right to assert copyright over any of those images it offers. From just their main page one can see they would have had to arranged agreements with FOX for The Simpsons rights and the NFL for team logo rights.
Here's a link to the Fantastic Four Movie official site. http://www.fantasticfourmovie.com/ If you dig through the Flash, you'll find some wallpapers http://www.fantasticfourmovie.com/us/flash/Wallpapers/InvisibleWoman/1280.html. desktopexchange.com also has these images and is simply redistributing official promotional imageshttp://www.desktopexchange.com/gallery/Movie-Wallpapers/Fantastic_4_InvisibleWoman.
Here's another site with the images, which includes a copyright statement: http://www.actuacine.net/fantastic-four-wallpapers.htm
Not that that makes a whole lot of difference to the question at hand, except for complicating matters a bit. I guess it is an example of what Jafo mentioned--multiple sites offering the same images with different takes on redistribution. In this case it is easy to see who holds original copyright, but this isn't always the case.