Star Wars Rebel Assault II for the PS1 didn't have much of any bosses, but it had a pretty stupid level.
I think it was level 3, you somehow had the Falcon and you were going through this rocky tunnel. Completely different from most of the rest of the game, you were in a 3rd person view, which already screws you up a little. You're used to being in first person in a ship. But then it gets worse.
As you go through the level, the camera moves and shifts around, really fast, to follow you through. Problem is, the ship doesn't go with it. Added with the tight tunnels, and the fact that the Falcon is as wide as hell, this meant you'd basically be slammed into rocky walls all the time. Death was certain. Sure, you could go vertical, but then you'd be tall as hell and hitting the ceiling. Only took a few hits too, until you exploded and were forced to start at the beginning. Hell, it wasn't even that long of a level, but it was still really lame.
Ruined my childhood, that level.
I got really lucky getting through that one. Although, maybe this is one of those things that got easier when you got older? Does anyone else remember this being so hard, or do I suck at videogames? probably the latter