What is Onyxia?

ok now i havent see it before, i've only heard here and there.

So far i think it is a flying dragon that cannot be hit by melee, only range damage, causes Fear (duh).

After reading up:
http://www.wowwiki.com/Onyxia

Orrrh, ok ... so per kill of these give 3-4 Scales for onyxia, that is if the raid survives AOE 6k Shadow Flame DMG. crazy stuff.
mutterz ...

Here's a clip where 8-men killed onyxia. wth!
http://www.warcraftmovies.com/movieview.php?id=17575