If you liked the Elfen Lied anime, the Anime-Planet community thinks you'd like:
In a post-apocalyptic future, Abel Nightroad does occasional dangerous work for the Vatican, to whom he is extremely loyal. While the apocalyptic war has long been over, humanity is still entrenched in a shadow war against the vampires. Lady Catherine, the leader of his operations group "AX," seeks to prevent a renewed full-scale conflict, but there are many forces on both sides bent towards war. As Abel and the rest of AX try to stop this, he encounters a young girl who will be the key to humanity's survival or demise. Now, Abel must not only fight for humanity, but also try to face his regrettable past...
Both Elfen Lied and Trinity Blood feature a main character who can be a sweet and innocent person who makes you smile or a blood-chilling killer who chops your head off. It's fairly rare to find someone who changes that drastically, but Abel and Nyuu both manage.
Cross Academy is a school with a difference: in a unique and experimental setup designed by the headmaster, it has a Day Class consisting of ordinary humans and a Night Class filled with vampires. Yuki Cross and her friend Zero Kiryu are school prefects whose job it is to make sure the secret of the Night Class is always safe; they patrol the school grounds at night and supervise the switchover of classes at dawn and dusk to prevent any 'accidents' from happening. While Zero is suspicious of vampires and hates the idea of sharing the same space as them, Yuki admires the Night Class for their beauty and sophistication; she is especially intrigued by their charming leader, Kaname, because he once saved her life. However, as Yuki quickly learns, not all vampires are amiable like the Night Class, and as terrible events unfold, Yuki must ask herself whether in a world where vampires are the hunters and humans are the prey, peaceful coexistence can really be achieved.
Vampire Knight is an anime mostly based on romance with action as well. With a rather surprising turn of events in the series, I highly recommend that you watch this anime. It is not as bloody, disturbing, or awesome as Elfen Lied (then again not much is), but it is still a great anime with a very good plot line.
In the year 1999, Tokyo has become a battleground as the Seven Dragons of Earth and the Seven Dragons of Heaven fight to determine the fate of the world. The one with the power to decide which way the battle will go is a youth named Kamui Shirou. Will he join the Dragons of Earth and preserve the planet by ending human life, or become a Dragon of Heaven and protect humanity from ruin? The fate of all mankind lies on Kamui's unwilling shoulders as both sides clash to gain dominance. The Dragons on both sides are individuals gifted with superpowers and fated to participate in this final battle, but what end will Kamui choose?
Both Elfen Lied and X have the same kind of feeling when it comes to death. Death/murder is portrayed in a very morbid and shocking way. Also there is a hint of innocence as "Lucy" and "Kamui" both have a lack of understanding about the situation/s that they are placed in.