If you liked the Elfen Lied manga, the Anime-Planet community thinks you'd like:
There are human experiments preformed and when these super beings make their escape they are ruthlessly hunted. Lots of gore and blood follow suit making both series action packed for a mature audience.
In a post-apocalyptic world, humans, robots and cyborgs live in the Scrapyard - a landscape of twisted, rusted junk made up of the garbage sent from the above city of Zalem. In this place, the inventor Ido finds a partially-destroyed cyborg amidst the rubble, gives her a new body and names her Gally. With no memory of her past and an instinctual ability to use a powerful martial art known as the Panzer Kunst, Gally matures and relearns life's lessons while she travels the broken landscape, struggles to remember who she is and where she came from, and discovers the mysteries of Zalem.
Both series star a non-human woman with superhuman powers (although the star of Elfen Lied is more of a villain, while the star of Battle Angel Alita is clearly a hero). Both stories are very dark & violent, and raise questions about what exactly defines "human".
Blood+ and Elfen Lied have female heroines that take part in a battle not only with the demons around them but also within themselves trying to figure out who they really are. They are not humans but are trying to take place and live in a humane world in which the lines of what is right and wrong are tested. Both series deal with a great deal of violence and questions about humanity as a whole and the ideals humans’ represent. Both deal with hardships of the main characters and tests the powers of each individual.
In 2010, the Britannian Empire enslaved Japan after a brutal month-long assault; in the aftermath Japan was renamed Area 11, and its people began a hard and terrible existence. Lelouch, a Britannian student living in Area 11, has grown up hating the Empire and everything it stands for. One day, while investigating a crashed military plane, Lelouch meets a mysterious girl who grants him the ability to control minds. Can he use his new power to fight for freedom, or will his hatred twist his good intentions into mindless acts of vengeance?
Middle school student Ganta Igarashi witnessed the slaughter of his entire class by the mysterious 'Red Man', and as the only survivor, he was labeled a mass murderer and sentenced to death. Now an inmate at the privately-owned prison and ‘amusement park' known as Deadman Wonderland, Ganta must try to survive in a place where inmates are the main attraction in brutal gladiator-style games. At the same time, he must attempt to uncover the truth behind the ‘Red Man', his mysterious childhood friend Shiro, and why he was the only survivor that bloody day.
Both Deadman Wonderland and Elfen Lied have super natural themes of super humans with advantage to kill. Also, they both contain strong violence and a very dark theme with and few comedy sides to it.
It also contains a split personality character, one being sweet and 'dopey' the other being a malicous killer.
I would strongly recomend this to the male fans of Elfen Lied, but of course girls would love it to.