Elfen Lied is gory, dark, and very beautifully written. The first episode is infamous for it's heavy handed use of gore, and is not for the faint of heart. If a bit of violence does not deter you, I would highly suggest giving this show a shot. It is a one of a kind Anime that a lot of people will love. (WARNING: This show does over sexualize some of it's younger female characters, which I deducted a star and a half for.)
Action horror and supernatural drama. Very gorey, can be cruel. There is nudity and it can turn quite disturbing.
Story about a mutant girl who has a split personality, one moment ''harmless'' and sweet, other moment a serial killer. I liked it better towards the end.