If you have a site distributing wallpapers with hollywood celebrities on them, would you get sued? Especially if you are distributing them for free? What would be the violations then?
big $$$ if you use pictures from the wrong photographer/agency your site shut down ... celebrities themselves can also sue if you post pictures of them that are taken in private without their permission (ie by paparazzi that climb over walls, ..)
As long as you took the photographs of the celebrities yourself or you paid the appropriate license fees to use the images you should be fine. If you didn't, you can be liable for copyright infringement. Under US law you can be liable for up to $150,000 in statutory damages. Since you aren't in the US, I don't know what laws apply to you, but at the least your web host may take your site down.