There is the Maker of Ruins which kinda looks like a funky huge beetle if i remember right. One that looks like a huge ghostly-type head. And one that looks like the dominions application icon for OSX (dunno if it's the same for PC) I think that one is the eater of gods.
To make a long story short, you DON'T want to see those doom horrors cause they are quite nasty
. I've had a few SCs kill the doom horrors but the fights were pretty close and this was an uber-decked out SC. If I remember right the higher end horrors have armor negating attacks with like 6 or more attacks and do crazy damage.