I'm definitely throwing my lot into this. I got ideas already. I'm thinking a sort of slime monster which may seem innocent enough, until it manages to eat enough creatures/people and start incorporating their flesh into his being. Goes from an ooze creature to a fleshy abomination. As for class, I think Brute fits his style the most, though he does have a dash of hunter as well. The type of creature who lies in wait, stalks his enemy, but once he shows up he just goes nutso. 

Some other ideas I have is a skeleton marauder of a sorts. Specifically, he used to be a holy warrior but has lost pretty much all of his magical powers, but also gained a new purpose to fight, so in between killing adventurers he preaches about his deity and tries to convert people. So kinda like a Zealot but with less emphasis about magic and more about bashing skulls.