User Recommendations for Shiki

Both anime contain non-human beings who kill humans. Another similarity is the huge amount of gore and mass killing but worth mentioning is that they also make you pity these non-human beings.

Shiki has a similar theme to Elfen Lied, questioning the humanity of people who aren't entirely... human, along with the humanity of humans themselves. In both cases, the non-human people have an instinct to kill humans, to survive and/or reproduce. There's a lot of moral grey areas; Shiki presents two characters with conflicting opinions, and with Elfen Lied, the question is tackled on a larger scale, although there is one character who is very conflicted about it. The execution of Shiki is a bit better, both in terms of character and plot development, although both anime are unrealistic with blood, and for some reason breast size

Similar themes about how evil people can be, and both are very interesting

It does have so many lore and history, is entertaining for watch and have similar genres

Both Shiki and Elfen Lied show us that even the "monsters" have their reasons for doing something, not out of pure evilness but rather the feeling of loneliness and isolation while also trying to survive.