RPG with Online Co-Op for Xbox 360?

Does such a game exist? A friend and I have been looking for a RPG we can both playing online together. The closest thing we've found is Fable II, but the online co-op stuff was thrown together haphazardly and wasn't fully fleshed out at all. Epic single player RPG's like Oblivion, Mass Effect, Fallout 3 and Dragon Age would be incredible to play co-op via Xbox Live.
 
Can you guys think of any RPG's that offer Co-op game play for the Xbox?
 
Thanks for the suggestions!

Fable III.

Borderlands.

" Borderlands. "

Borderlands is RPG-Like. Earning XP, leveling up, getting loot.  
 
The main story lacks some epic-ness, but (most) of the DLC is pretty solid on narrative. 

Only one that comes to mind is Too Human. Not a game you play coop for story though...

Yeah we did Borderlands already and that was awesome. I'd classify Borderlands to be more of a FPS though, than an RPG. Is Fable III's online co-op better than it was in Fable II?

Resident Evil 5

" Yeah we did Borderlands already and that was awesome. I'd classify Borderlands to be more of a FPS though, than an RPG. Is Fable III's online co-op better than it was in Fable II? "

" Borderlands. "

" Fable III. "

Fable III's MP is done 90% right - as the guest you can't save or effect the story in any way but you get your own Hero from the Single Player all other parts of Character growth are intact.
 
Sacred: The Fallen Angel, Too Human and Marvel Ultimate Alliance (stay away from MAU2) all fall under the Diablo or Gauntlet style RPGS - kill a lot of shit, level up, maybe get some gear and upgrade your abilities. 

Sacred 2
Huge map, up to 4 player co-op, 500 side quests and a fun story.. what more could you want?

I think the new Two Worlds game is going to have online. I think the first one did too. I'm not sure though.

There is no such game.  About the only "co-op" RPG that comes
close to the RPG part would be MMO games on the PC.  I don't
really consider Borderlands to be RPG & Fable...that's crap.

Two Worlds 2 is only one i can think of.