Was the Rat King really a villain in Mirage canon?
 

He only face the turtles one time in Mirage comic, He seem more of mysterious character rather than an actual villain.

Only in his first issue.

They sorta turned him into on in the Tales Volume 2 issue where they made up that stupid origin for him.

I'm not so sure that origin is canon. It's not mentioned anywhere in the Universe book...

I'm not sure if calling him a villain really works, but he definitely wasn't an ally, either. I think that's what makes him so interesting, honestly. And you should really check out the City at War arc. The Rat King really shines there, in my opinion.

The "origin" was awful. It better not be canon.

Yeah, that origin made more sense for the Archie universe Rat King, not the Mirage one.

I prefer Rat King to just be some maniac who lives with rats...attempting to give him a backstory just ruins him.

love the City at War take...

I assumed it was. Everything at this point seems to be or I would imagine so unless stated otherwise. It also makes some connections as to what happened to Splinter after he died.

If it's not in the book I don't know then but I assumed everything coming out now was cannon.

There are a few details of stories in Murph's entries to the Universe book that tend to exclude events from stories he wrote (and that, based on the range this Universe book is reaching issue wise, should be in there). A number of stories by Bill Moulage -- in fact, just about everything, seem to have been left out. I'm going to be putting bits and pieces back in where they fit, but we'll see what stands come December I guess!

He actually save Spinter in the City at war arc, by telling him to eat a rat in order to suvive.Even in the old toon The Rat King helped the turtles once.What made him great is that he's a neutral character, Sometimes he a foe or an ally.

Rat King/The Monster was never a villain... but certainly no hero, either.

I don't see in what way he wasn't a villain in "I, Monster." He may be delusional, but he's just a straight up antagonist in that issue with no hint of duality.

Even looking at the end of the issue, I have a niggling suspicion that Mirage intended to set him up as a recurring villain a la Complete Carnage, but never got the chance to use him again until he was re-defined in "City at War."

About how many characters are covered in the MU book, and is the format similar to Marvels old OHOTMU or like the recent DC Encyclopedia?

From his later appearances we kind of have to apply a layer of duality to his first appearance in Tales.

Was Bill Moulage another Murphy pseudonym? The guys only credits are some random TMNT stores and Puma Blues. Plus it seems odd that Murphy would give this guy work but then seemingly single out his contributions and omit them from the sourcebook.

Kinda seems like maybe he used that name when he wasn’t particularly proud of a story.