The Beast and The Sigil by enhypnion
Here is a bit of background information on the character:
He is a footsoldier of a hellish army. Not very bright, but then again, he doesn't need to be very bright for what they are created to do. Imagine hundreds of thousands of these things rushing at you, and no matter how many you kill, there are always more coming at you replacing those you just killed. They are expendable, but brutal and completely ruthless. All they know is war, born to fight it and expected to die in them. There is no such thing as a 'retired' one, they all die in the battlefields.
They sometimes use a rather scary looking curved sword, which looks more like a hook, but not all of them have weapons. Most of the time what they can do with their hands is horrible enough.
They rarely use their horns, and over time they have become more of an indicator of how long that particular demon has managed to survive. The longer they are, the more likely that its owner is a veteran of many battles.
Software: Photoshop and Illustrator (the sigil)