http://tvtropes.org/pmwiki/pmwiki.php/Main/ThatOneBoss
This is where you post/rant about that one boss you're stuck on and absolutely hate.
For me, it's Minotaur in Shin Megami Tensei IV. Quite possibly the most brutal first boss ever, and that's even on the easiest difficulty. Betweeen hitting hard, potentially being stuck with the guy that spams magic he absorbs, and being stuck trying to get demons with magic he's weak to, it can be a really painful experience.