The best boss fights EVER!

[Demosthenes2k8]

The final boss (can't remember his name) in TWEWY-amazingly tough when you have crappy pins
Diva of the Twilight from Lost Magic-Just amazing how it went on for almost 10 minutes (the time limit) when I had a completed spellbook and mazed out monsters.

 

[dadevvtsvre]

That one boss in LoZ: Twilight Princess where you fight the boss in the desert place was pretty cool.

 

[mehungrey]

I love the Zant fight from  LOZ TP and the battle against Axel as roxas (Because you get two keyblades the whole battle :lol From KH2.

 

[Yggdrassil]

2nd Chapter Boss in World Ends With You.

He summons tons of tough noise before coming down himself, and you can hardly damage him without holding the light puck.

 

[Demosthenes2k8]

EDIT: Oops!

The final boss in Golden Sun: The Lost Age. It's not so much the boss as it is the secret about it...

 

[Haki]

I think the best boss is Zodiark from FFXII. I fought him like 20 times before i could defeat him. Yiazmat is also tough.

 

[BellGoRiiing]

I need to add GlaDOS, even though she (er...it?) wasn't really a final boss...it was hilarious.

 

[Dissonance]

Pretty much every assassination fight in No More Heroes.

Especially Shinobu, Bad Girl, and "Dark Star".