Arrrgh MineCraft Overhaul (AMCO)
The best shots from this pack.
In this modpack, HE can spawn, and HE can kill you with only one hit.
I played at night, and saw HIM on the roof... God, I've shit bricks at this moment.
When I hit HIM with diamond sword - he dissappeared, and "Herobrine disconnected" were typed in chat.
So yeah, that's a Humans+ mod, which adds Wanderers, Miners, Survivors, Hunters, etc. And two main villans in this mod - Herobrine (HIM) and Dark Knight. Last one can spawn ONLY in the Nether area.