I wish to release a game with a creepy pasta called "Jeff The Killer". Can I do this without getting copyrighted or sued. Or can I do something which allows me to release the game with none of this happening.
I do not believe the original JtK was copyrighted as the author is unknown and there's no official licensing on the original. I've also seen no dearth of video games featuring Jeff so I can only assume that it's not a restricted IP. You can contact one of the developers if you want to be extra cautious.