Murai(first boss) in Ninja Gaiden on Xbox.
Good god, getting used to the controls and actually passing the level is hard enough and requires many tries in itself. Then when you finally manage to get to the boss and congratulate yourself on learning to play this game, the game goes:" Sorry kid, but you SUCK". He kicks your ass. Many times. It took days to beat him, and the fact that he displays his skill with the nunchaku every time you go up against him, doesn't make it any easier.
When you DO beat him, it is revealed that you are only training in a friendly manner. Just sparring, that's all. EXCEPT he has killed you about hundred times. YOU ARE DEAD written in blood across the screen every time you lose.
But that's how ninjas roll.