well i didnt read through the WHOLE post but i doubt anyone mentioned this one. Hardest boss is definatly General Akboob (and his strange giant robitic hitler head) from the arcade game Total Carnage. I'd be willing to bet to feasibly beat that boss it'd take at least 10 dollars in quarters.

The last guy one Far Cry, can't remeber his name. I had to cheat to finish the game. I know... I know.

I didn't read the whole thread, so I'm not sure if someone already said this Boss, but here goes.

I always liked the fight with Vulcan Raven in MGS. The style of fighting him is interesting, and all the noises of him stomping around and that chain gun warming up are just plain chilling. My $.02

The Butcher from Diablo! LOL, awesome.

He was totally kick-ass.

Also, the final boss in "Vampire: Masquerade." I'm pretty sure even with cheat codes I had a tough time beating him. I think I rezzed my party like 25 times in that battle.

Okay, now THAT's a hard boss.