Quote Originally Posted by Kawaii Ryűkishi
It's impossible to lose the shirtless Sephiroth and Yu Yevon fights, so they don't really count as last bosses. They're more like story scenes that just take the form of battles. Therefore, Sepher Sephiroth is FFVII's last boss, and Braska's Final Aeon is FFX's.
Kishi knows all. Do not bother to argue.

I never knew FFXI had a 'final boss'.