2 here, both with rogues (though I've seen great players in all classes):
#1 - In early cata prot was pretty solid when geared (well as geared as I ever get). I was in Tol Barad Peninsula up near Largo's Overlook, looking for people to gank, running solo and not fearing much. Saw this rogue and I was like 'ur mine baby.' Opened up on him and then something happened. I lost total control of the fight. He played me like a music instrument. I blew absolutely every cooldown I had, Lay on Hands included, to reset the fight, and he still never went below 90%. I see/feel that sometimes, but not at that level of skill very often at all, then a couple of days later.....
I was running with 3 people, all of us in vent, doing dailies in Tol Borad finishing up and there he is again, minding his own business questing alone and I am like: 'Pay back time biotchh!...can't beat ya solo, ur mine now!' Well he locked down the fire mage with us, let me beat on him, blew up our holy priest. Locked me down, blew up our mage, then looked at me levelly and proceeded to beat me silly. I was sitting dead in body watching as he went right to questing like nothing happened, and I never saw him again. I'll not forget that rogue.
#2 - Back in Vanilla. Another rogue. This one was EVERYWHERE. Ashenvale, yep he'd pop out of stealth, kill me, then move on. Stranglethorn Valley, the same. Desolace, same thing. He did that to a lot of people I think as his name was spoken with something like awe. The one day we're doing those two dragons (I think it was) that used to exist on the east side of the Badlands....the quests with the elites. I'm assisting someone and boom there he goes, three of us down, and then he stops, waves, helps me kill the dragons, disappears, and I literally never see him again. I think I was about lvl 50 paladin then (having bumped into him from 30 until then). Not forget him either. He gave me my first real 'look over your shoulder' wpvp feel ever. It was pretty awesome looking back.
I'll add one other addendum...I still remember the feel of seeing a full 40 man Horde raid riding worgs through southern Searing Gorge to Molten Core after massing in the Badlands. Ohh, the blood was high then! //////CHARGE!!!!!!!
Edited by Bordak on 4/26/2013 1:28 PM PDT