That One BossS

In video games, there are two types of challenges. One type is the overall difficulty and you have to beat the game by mastering the game mechanics (and have lots of patience when losing over and over again). The other type is that one boss who is so hard that you lose against him the first time around. This boss will be both a warning for you (the game is gonna be even harder) and a personal goal for you (when I can defeat him next time, I'll have defeated my inner demon!).
Today, I'd like to talk about the greatest boss I've ever met: Lu Bu from Dynasty Warriors 2.

Lu Bu wasn't my first big boss in my live. The earliest one I can remember was Doel from The Legend of Dragoon. I couldn't win against him no matter what, and I was kinda lazy to go back and train some more. I replayed through the entirety of Disc 1 just to be strong enough to defeat him. But Doel was just a wall I tried to climb, but never succeeded. Lu Bu, on the other hand, was a cannon. A monster. A guy who defeated you in just a few hits.

Let me elaborate how things work in Dynasty Warriors: You must defeat an officer or general and collect a stat-increasing item he drops – that's the only way to level up in this game. When you play the game for the first time, you don't know that yet and therefore don't replay the same first level again and again just to be moderately strong.
So after finishing the first level, I play the second one “Battle at Lu-Hao Gate”. You might lose some health here and there, but you're still good to go. And there he is, a guy I though I could defeat – instead, he utterly destroyed me.

Needless to say, I stopped playing the game for that day. Too big was the humiliation.

Eventually I started playing the game again and beat the level – by avoiding Lu Bu. He is supposed to be an enemy you face after you've increased your stats close to the max. In other games he is still very tough, but at least is ridiculous strength is pointed out properly. Eve to this day, I still have fear to face him in one of the newer Dynasty Warriors games. This guy WILL break you!

Do you have a boss encounter that shocked the hell out of you as well? Feel free to share your own stories here.