Guardian of the Frozen Throne. Pieced together from the bones of a thousand vanquished adventurers. The first challenge your raid must overcome if you hope to defeat the Lich King.
Such wasted story potential.
Unlike every other boss you face in Icecrown Citadel, Lord Marrowgar is the only one without his own distinct backstory or ambitions. Saurfang & Sindragosa are trapped against their will, Lady Deathwhisper seems to be some kind of evil recruitment officer, and Putricide is off doing his crazy experiments...they've all got their own individual personalities and flavor.
Lord Marrowgar, on the other hand, is pretty lacking when it comes to backstory. In fact, if not for the flavor text of the weekly quest to kill him (Lord Marrowgar Must Die!) we wouldn't know ANYTHING about him.
Oh, he definitely serves his purpose as Arthas' evil doorman - visible and ominous as soon as you enter the citadel, fight mechanics just complex enough to shatter unprepared pug groups, oh and SCARY/AWESOME AS HELL model design.
But just who IS Lord Marrowgar? We never really find out. This would be perfectly acceptable, and I'd be willing to just write him off as a generic guardian who simply monitors the front door...if not for one little detail. A detail that, for months, meant nothing to us.
He and Arthas say the same thing when defeated.
When I first saw the "Fall of the Lich King" cinematic, I was extremely interested in Arthas' final line of "I see... only darkness... before me." In terms of Arthas' final fate, it's a great line - tragic and lonely, but not necessarily apologetic. It's superbly vague.
But I didn't care about Arthas. I was immediately struck by the curious repetition of Lord Marrowgar's "I see... only darkness..." death quote. Which really, when you consider Marrowgar's other quotes (all rather standard DEATH! SCOURGE! BONES! fare) and think about who said it (an undead monstrosity/golem/THING created solely to kill adventurers!)...it really doesn't make a lot of sense. You would expect an angry, vengeful denial, or something about how we are doomed, etc. But instead, Marrowgar seems...oddly mournful and regretful.
So why the repetition? No other boss in ICC echoes anything the Lich King says. Is this supposed to imply a more significant connection between the Lich King and what we assumed was just a gargantuan Scourge minion?
When people first killed Anub'Arak in Azjol-Nerub, his death quote of "Never thought... I would be free of him..." was heavily inspected and analyzed by lore-lovers to determine if he was a loyal servant or slave. But the Fall of the Lich King cinematic wasn't released until many months after people first starting killing Marrowgar...perhaps we had all grown so accustomed to his death quote that we didn't even notice the duplication.
So what exactly DO their shared last words signify? Clearly Lord Marrowgar is more than just some mindless skeleton servant - there's some kind of deep, meaningful bond there. Personally, I think he's part of Arthas' soul or spirit somehow - he would almost have to be. Unfortunately, there are no answers to be found, because lore and history about Marrowgar are nonexistent. It's a real shame. Mr. Booooonestooooorm could have been another Matthias Lehner - instead, he's just one of countless generic raid bosses that are just there to dispense loot and shinies.