General RAAM from Gears 1 on insane........

I still have nightmares.

The final boss of the Conan game.  He's not so much "hard" as he is "obnoxiously over-drawn and irritating."

Also, the final bosses of almost every fighting game--especially the following:  Tekken 6, any Mortal Kombat after 1, Dead or Alive 3, Tekken 5, Mace: The Dark Age, etc. 

These bosses aren't so much challenging as they are cheap and programmed outside the set rules of the game they're in.  The final boss should be challenging, but it shouldn't be operating outside the norm of the game what with killing in three hits (Tekken 5, Mortal Kombat whatever), being stupidly oversized (Tekken 6), or forced to fight from an awkward angle (Dead or Alive 3).  Honestly now, if I'm fighting something that takes up 60% of the screen and my hits only ever reach his knees, that's just bad design for a fighting game.  Eyedol was one of the best final bosses I've ever seen in a fighting game because he was powerful, impressive, but fought within the rules of the fighting game--it was fair. 

For the issues I had with Seth in Street Fighter IV--at least he largely operates within the rules of the fighting.

Good call about those fighting games. Jinpachi and Azazel soooooo cheap.

Ha ha, thaks.  Here's a clue how I feel about Tekken:  Tekken 3 made me buy a Playstation.  I absolutely love the control, the fighting system, and many of the characters.  The best thing, though, is the varied, though balanced fighting system--which is completely butchered if not outright ignored by the inclusion of such cheap bosses.  Ogre and True Ogre, at least, still kept with the rules of the game.  Azazel, on the other hand--fucking infuriating. 

I want to be able to fight the final boss with the same skills I've been building playing the game normally.  With such cheap bosses, not only does it waste the time I've spent honing my skills--but if often requires cheapened gameplay that reduces the effect of actually toppling the boss.  Spamming one or two successful moves or repeatedly mashing the same attack, crap like that.  I remember fighting Shao Khan in Mortal Kombat II and 3, and I was essentially forced to spam the same special move over and over in desperation to win, which made my victory feel cheap in the end.  The bastard could kill you with 2 or 3 attacks. 

I still think Eyedol in Killer Instinct (SNES) was one of the best. 

I think Azazel is probably about the worst so far.  Oversized, awkwardly shaped--90% of the attacks are against his knees, and a good 50% of those seemed to never even affect him.  I want to punch Tekken 6 in the face.

Ikaruga's final boss;.

It was so hard I never even reached him...I probably could with more practice...But everytime when I am getting better in the game I also get tired of the game =p.

Hmmm... can't say this is actually the hardest I've ever faced but from recent memory Flamelurker on NG plus in Demon's Souls busted my balls.

Yep, all three of them

Megaman ZX final boss on hard. Just getting there is insanely annoying, and even if you have 10 livs to bweat him like I have everytime I go there, you still get your ass royally kicked.

The "boss" races in F-Zero GX in story mode on Very Hard... I hated them all

Talking about Dead or Alive....I really had an issue with the end boss of Dead Or alive 4 X_X.

Tales of Symphonia - Abyssion

Tales of Vesperia - Brucis

Monster Hunter Tri - Deviljho