Realm First! Grand Crusader

actually, Not quite. 24 People can die on every boss as long as you 1 shot each boss. (In Grand Crusade you have a total of 50 attempts for all bosses.) But indeed, you should be quite proud for earning this.

Although wowhead shows that the title reward is "The Grand Crusader", the title this achievement awards you is actually just "Grand Crusader", which comes before your avatar's name rather than after it.

Link: http://static.mmo-champion.com/mmoc/images/news/2009/september/premoinsanity.jpg

This Achievement is still attainable in Cataclysm, and was attained a couple days ago on Grizzly Hills US.

Juicy, important details:

-You can wipe as much as you like, and still attain it.
-Anub is by far the most challenging fight. With a decently geared/competent raid group, it is possible to burn thru his health, and 2 sets of adds without an underground phase.
-Asking your DPS to take off their gear, then put it on right before the pull is a fantastic way to lower their HP pools for the heroic Anubarak encounter.. Remember, raid damage is non-existant in the first phase, so ensure your healers/dps are instructed to keep their HP as low as possible. Life taps and SWDs are highly recomended before the phase change at 30%.

Good luck on your server first kills if they're still up.