Me, when even when I'm not logged in.
Jaina. She tanked the Lich King and part of her is pure arcane magic now!
It'd be strange for one such as Velen to not be incredibly powerful. He's shown no indication of being frail because of age, either.
Along with the fact he twisted Xavius into the Nightmare Lord, and Azshara serves him.
He has the some of the most powerful beings to ever step foot on Azeroth's earth on his side, and he's every single one of their Masters.
You can only imagine how powerful this guy is.
OH, did I mention he waged war with C'thun AND Yogg Saron?
im gonna say jaina, it's not everyday that you get regarded as the most powerful sorceress on azeroth, after the nuking of theramore she got more powerful than she was already.
of course there is also azshara.
"any man shaving for a woman should relinquish ownership of his testicles aswell"
I would think it is in between Jeremypwnz, Kael'thas (He won't die), Ragnaros (Also won't die), Onyxia (Still won't die), Garajal (Coming back in 5.2), Nefarion (Won't die), Hogger, or Viscidus.
On a serious note, I would like to think Thrall (purely because he is such a badass and helped with Deathwing and all) or M'uru.
Super saiyan 2 jaina hands down.
"A democracy cannot exist as a permanent form of government. It can only exist until the majority discovers it can vote itself largess out of the public treasury. After that, the majority always votes for the candidate promising the most benefits with the result the democracy collapses because of the loose fiscal policy ensuing, always to be followed by a dictatorship, then a monarchy." -Alexander Tytler
Azshara. She was right up there with Archimonde and Kil'Jaeden TEN THOUSAND YEARS AGO. She's probably gotten even more powerful since.
He is the life of guilds he has never joined.
He once had a noobish moment- just to see what it felt like.
If he were to beat you in a duel, you would have to fight the strong urge to thank him.
The Lunar Elders have a holiday in which they honor him.
He can speak Darnassian. In Orcish.
He is: The Most Interesting Man in the World of Warcraft.