He's called the Abhorrent Beast. Remember that suspicious cannibal guy in the Forbidden Woods? If you send him to the Chapel instead of Iosefka, he starts murdering NPCs. And eventually turns into this. If you attack him at the woods you can fight him in this form there too.
He's also a Chalice Dungeon boss (Ailing Loran). He's very difficult, one of the hardest bosses in the whole game, at least in the Chalice version.
I'd like to clarify that these are not photomode despite the camera angles; they are from replays. For those unaware, you can use photomode in replays but they are real-time by default so the IQ isn't enhanced at all.
I do remember him, and I remember how I sent him to Iosefka after seeing all those messages around him, telling me not to trust him. Similar to those messages near Iosefka's Clinic... which helped me, since I would probably send an NPC or two to her if there weren't any messages there. (Yes, I can be that naive.)
Anyways, here are couple of my screens (both JPG, taken before 3.0).
And btw, great shots of DC everyone, keep them up! Easily one of the best and most beautiful PS4 games out there.