Oct 7 2012 - one of the hackers who went across different servers with a level 1 char, flying around and insta-killing everyone. Happened over several hours, filling Stormwind with death. Initial reports of the Rapture were found to be incorrect.
Here's a vid of the it being used from the dude who did this: https://www.youtube.com/watch?v=Fb-1FpPpBRI
For all those asking - the combat log said "You died." without any damage source. The hacker was the level 1 priest (if that isn't immediately clear) that's flying around.
Music - Gustav Holst "Neptune the Mystic"