Gruble the Poop Muncher is a villain. He is persumably human(?) and, as his name suggests, is known for eating copious amounts of human (and non-human) feces. For obvious reasons he does not have an image on this wiki.
Gruble the Poop Muncher eats loads of poop on a daily basis, eliciting disgust from many of Mike's followers, but also garnering respect from the rest (who also happen to partake in the same activity.)
Unlike other villains, he does not actively antagonize Mike or his followers, rather, he hangs around the chat like anyone else. Every so often, he opens his ugly mouth, with shit dripping out of it, to spew whatever he wants around everyone else, trying to convince them to follow his way of life. Most people have enough sense to avoid him and ignore whatever he's trying to say, but certain others buy into it completely.
Some have theorized that his ultimate goal is getting Mike himself to endorse his way of life, but this is unconfirmed. However, so far this remains the only plausible theory of such a thing.