What do you think is the most Unfun boss in the game?

I'm not talking about hardest, but just one that every playthrough you do you dread having to fight it.

For me it's the double Crucible knight fight, I know it's not a mandatory boss but my God it's the most unfun fight I think I've ever done. Especially this playthrough where I'm playing a melee bleed build...and crucible knights lack the component that makes bleed builds effective

Thankfully since I'm not playing str/faith this time around I can skip them this ho around