you know how every shonen anime has a boos at the end of story
ex: naruto-madara bleach(azien, but i didnt finsih reading the manga) so what's fairy tail
eh, fairy tail changes bad guys every time it changes arcs so it's pretty much diff people...i want to say zeref though, since it seems like from the very beginning, people have been trying to resurrect him...in the manga, he appeared, but the lady who wants to resurrect him the most (you know the daughter of gray's lady master? her), said she was going to awaken him...maybe she was talking about awakening the evil in him b/c he said himself he doesn't want to hurt anyone