I'd like to add Ornstein and Smough (two bosses in one) from Dark Souls. I almost broke my controller on my first run through the game when I got to that boss.
I rarely "rage" at a game, but that boss was straight bullshit.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin