Pantheon: Vile Deities
Book of Vile Darkness for D&D 3.0 describes several vile deities that could be inserted in any setting.
Sometimes I get an urge to make some GURPS content, be it something original, or something converted from another system/media. Maybe if I post it here, it will be useful not only to me. Keep in mind that I'm not a native English speaker and please forgive any mistakes.