Huh, nobody suggested Parasyte yet

thx ive read most of them
gantz is one of my fav mangas and it one good example for this

if you got any more just keep them coming

the blame series by nihei tsutomu?
hellsing
kekkaishi?

Bio-Meat: Nectar
Gantz
Kiseijuu
Shingeki no Kyojin

[img]http://i252.photobucket.com/albums/hh9/xsaranghaex/seigaku.gif[/img]