Bosses you still haven't beaten/took you the longest?

[deathbydeath]

I still haven't beaten Jade Empire or KotOR because of the final level/boss bullshit they pulled.

 

[shteev]

There's a big guy in Aquaria I'm guessing is the final boss I never got around to beating.... I couldn't figure out how and I never went back to it. I definitely feel like I'd like to wrap that game up at some point, it was fun.