The girl in the middle column, top row, looks like she's missing some brain matter, there.

She's the main heroine from an AliceSoft game called "Night Demon." You can find the CGs from the game on miezaru.

Adding the Carnelian tag because at least 3 characters (top row, middle, and third row, left and second row, right) were originally designed by Carnelian.

Third row third picture was originally done by Hiro Suzuhira wasn't it?

Akiha?! Breasts? Does not compute...

That's the great thing about fanart--it's up to the artist whether they follow the canon or not.

This appears to be a montage of a bunch of photoshops. Not badly done, I must say. :p

Girl with the silver hair and twin braids is Eun Ami from Unbalance Unbalance. What's the relationship between all these girls? Can't be seiyuu...