Just a few monsters for your consideration. Well, some might say monsters. Maybe they're just different. I'm not sure I'd take the chance to find out, especially with the one on the right. The one on the left, the spikes are supposed to look like they're coming from the inside, breaking through the skin rather than growing like horns might. I always feel at my most creative when making creatures that are at least a little bit 'off'.
In case my shading isn't contrasted enough (heh yes), if you zoom in on the middle dude, you might be able to see the teeth better. It's my fav.
with love - M