Here's another one for me: The Smelter Demon from Dark Souls 2. To be fair, he's an optional boss, so whatever torture you go through here is entirely self-inflicted. But since he's at the midpoint of a particularly tough level, and killing him gives you a bonfire that cuts the level in half, its pretty hard to say no. The Smelter Demon is a huge guy with a huge sword that can kill you in two or three hits, if you're lucky. Also, he's on fire. That means that you take damage just by being close to him-- which you have to do in order to hit him! From Software really showed how sadistic they are by putting this guy in this place. Screw him.
General and high profile video game topics.
The mud boss in the first stage of Wily's Castle in Mega Man 1. In the NES version, there is the 'pause glitch' that you can abuse to kill him, but in the later releases, like in Megaman Anniversary, it isn't there. I have never been able to beat that damn mud guy without the pause trick. Last time I tried this was last week. Never even got him to half way health, let alone close to death.