Greatest..boss..EVER

[Crop]

GLaDOS.

Really, why's that? Portal is definitely one of my favourite games ever, and GLaDOS was an amazing character, but I wouldn't consider the 'fight' against GLaDOS really a battle. But if you do, it was pretty easy and basic.

@eternal essence - I agree about the Riku fight. I forgot about KH. Both fights, with Riku, and then with Ansem shortly after were amazing imo, they rank up there with Kessler. Partly because (as you said) the cutscenes before and after.

[Alucard von Elru]

Most of the bosses from Twilight Princess, definitely! Particularly the water creature in the Water Temple, the aforementioned dragon in the Sky Temple, and the wicked awesome skeleton thing in the Arbiter's Grounds that you fight on that awesome floating disc (good god the name escapes me!). Twilight Princess is full of epic encounters!

I'll second the notion of the original Kingdom Hearts. I'm of the opinion that the series has gone way down hill since its brilliant debut, and the bosses are a huuuuuuuge part of the reason why. KH1 was a wonderfully challenging action/RPG, and nothing proved it better than its amazing bosses. The encounters with Riku, Malifecent Dragon, Darkside, Sephiroth, the Titans, and the final encounter with Ansem are all spectacular, though it must be said that nearly every fight in the game brings some great moments with it!

Shadow of the Colossus. Kind of obvious.

Every single boss fight and setpiece moment in Metal Gear Solid 4: Guns of the Patriots.

Most of the bosses in Shin Megami Tensei: Nocturne and the Digital Devil Saga games. It's exceedingly rare for an RPG to have genuinely involving boss fights, but these games succeed with style, creativity, challenge, and balance.

That's all I can think of for now! :P

[McLovin']

The final boss in Dragon Age was definitely a fun ass fight.

[NeoCracker]

I was actually severly let down by the final fight in Dragon Age.

(SPOILER)I wasn't anything special, it was you versus a Dragon. I was hoping for something a bit more spectacular then just another Dragon. Felt just like flemmeth with a bunch of goons.

[Del Murder]

I agree with many of the battles posted, like MGS and Twilight Princess.

From the FF series I would nominate the FFVI final battle, FFVII's Ruby and Emerald Weapon, FFX's Nemesis.

FFXI has it's share of intense battles. Some of the most intense I faced were against Alexander in the Treasures of Aht Urhgan finale, and the airship fight against Omega and Ultima in the Chains of Promathia storyline. That airship battle is widely considered the hardest mission in the entire game due to the 60 level cap and the 45 minute time limit given to win 3 different battles.

[Necronopticous]

GLaDOS.

Really, why's that? Portal is definitely one of my favourite games ever, and GLaDOS was an amazing character, but I wouldn't consider the 'fight' against GLaDOS really a battle. But if you do, it was pretty easy and basic.

Its simplicity is part of what makes it so great. It is designed to allow you to figure it out and win on your first try--having to redo this sequence would severely detract from the experience. The atmosphere, the context, the tension, the humor, and the feeling of sheer triumph when it's all over...It's hard to imagine a greater "boss battle."