But what counts as a boss in this context? If Hogger could count, he'd take it easily. I mean, he is a boss in his new home in the basement of Stormwind, sure, but he hasn't been for long.
What about raid bosses? Who's the most killed raid boss in the game? It's got to be the first boss of a given instance. Maybe Lord Marrowgar? I reckon, based purely on subscriber numbers, that The Lich King will be the most killed end boss.
What do you think?