Some of those are new to me. I'd be glad to know the artist aswell
I'm searching for this guy too. My profile pic on tumblr is one of these. I'm pretty sure Im following this artist on Pixiv, but I'm following over 300 people and having trouble finding this one guy. I'm trying to get this answer for someone on tumblr before the site dies. If I figure it out I'll post it here too.