Most Memorable Boss fights

IMO has to be Shadow of the Colossus, those things were huge.

Here's a list:

Cybil in Silent Hill
The final boss of Panzer Dragoon Zwei
Psycho Mantis
The Great Mighty Poo
Trance Kuja

Hell, you could probably count that as my top 5 bosses of all time.

Worm Boss in Gears 2

Ahh how could I forget Psycho Mantis? That was phenomenal.

"IMO has to be Shadow of the Colossus, those things were huge."

I'm gonna name a few that I really loved.

The Minotaur boss in God of War.
All the Ganon fights in Ocarina of Time, including Phantom Ganon.
Several of the bosses in Shadow of the Colossus, though my favorites were that flying serpent thing in the desert and the giant knight.
Pretty much any guy you fight in Mike Tyson's Punch-Out!!
Verdugo from RE4.

Mother Brain and all her carnations from Super Metroid.

Hmm, I really liked the fight against the End in MGS3, but I didn't really like the character.

Ruby Weapon in FFVII was pretty cool too, but he isn't really important to the story.

Crash Man in MM2 was mad hard the first time I fought him...

Akuma in SSF2T was also pretty hard.

It's really satisfying the first time you kill Shao Kahn in MK2/3, at least I thought so.

Ares in the first God of War was also a really satisfying end to the game.

I guess what I'm saying is, bosses become memorable for different reasons. The greatest boss fights can be great for different reasons. They can be hard, complex, a change of pace, satisfying etc. Some boss fights can be great because of their story significance.

Bison!

solid V liquid snake in mgs4

The Boss Fights that I remember most are the ones that I played over and over again as a child. So mostly N64 and GB stuff

Bowser - Mario 64
Ganondorf - Zelda 64
Gruntilda - Banjo-Kazooie
The Elite Four - Pokemon

Stuff like that.

Omega Zero in Megaman Zero 3
Sigma: MegaMan X
Twinrova: Ocarina of Time 
William Birkin: Resident evil 2 *fixed (Nemesis is A type of Tyrant if you read the science behind his creation)
Flying mech boss (soldier blade)
Bitores Mendex (RE4)
I Have some many more memorable boss fights but these are what came to mind

Tyrant: Resident evil 2

The flying sand snake in Shadow of the Colossus...nothing comes close to that.

Off the top of my head:

Kefka, Giygas, and Lavos.

Thread over.

"Kefka, Giygas, and Lavos.Thread over."

"StarFoxA said:

"Kefka, Giygas, and Lavos.Thread over."

i have no damn idea what your referring to "

was never in to final fantasy 

"StarFoxA said:

"Kefka, Giygas, and Lavos.Thread over."

Thread over indeed.Well, maybe the Mother 3 "boss" "fight"."

The only boss fights that come to mind are Mother Brain (Super Metroid) and Sigma (Mega Man X). I'm proud to say I've beaten both of them.

The Colossi(?) were memorable bosses but can they really be considered "bosses"? They are the only enemies in the game. Can a game consist of only bosses?

"Off the top of my head:

The Great Mighty Poo

"

This:

"This:
"

• There was nothing like the first time I fought the first colossus in Shadow of the Colossus.
• Sephiroth.  I know, I know, scourge of the earth, but after you killed him in big form, it just came down to cloud and him.  I think we know who won.
• There are others.  I don't really feel like waxing eloquent at the moment.

everything from shadow of the colossus, and ganon from zelda oot.

Pretty much all the bosses in Devil May Cry 3. This is because that game was a bitch to beat and when I finally did, I remembered how all those bosses were hard an yet I beat them all. That stupid Heart boss gave me the most trouble, stopped playing the game because of it. Went back months later though and kicked its ass.

Just about every bowser fight
Having to fight a giant cake in super mario rpg (seriously, how is that not cool?)
Ganondorf battle from OoT
Both Gruntilda fights
Crash bandicoot 2 boss fight with neo cortex
Having to battle gary at the end of the elite four in pokemon red and blue (yes I considered him a boss)
Mad Jack fight from DK64 (I hated that damn fight)

The last summon boss from Golden Sun: The Lost Age"

- Bitores Mendez  in RE4 because it was very claustrophobic and he looks creepy.
- The dragon boss in Twilight Princess because it had a great sense of scale.
- All the monkey bosses in Donkey Kong Jungle Beat because of the drum controls.
- Lisa Trevor in REmake. Not because of the fight itself but because of her backstory.

-Rufus Shinra and Dark Nation in Final Fantasy VII simply because the fight is stupidly easy, yet I managed to lose to him twice during my initial playthrough.  Yes, that means I had to fight the machine boss on the elevator twice as well.
-Albert Wesker and Bird Woman from RE5.  Sure, the story sucked in RE5, but finally going up against series baddy Albert Wesker for the very first time since acquiring his superpowers was pretty awesome.
-Frank Fontaine from BioShock, due to its extremely off-putting and out-of-place nature.  Does something have to be good to be memorable?  Didn't think so.
-Yunalesca from Final Fantasy X
-Judge Gabranth from Final Fantasy XII

Gannondorf from Wind Waker and Twighlight Princess
Kefka
Dr. Robotnik's death egg - sonic 2
Metalhead or hammerhead? -vectorman
Omega Pirate-Metriod Prime
Every boss in Metal Slug Series.

Edit*Mutoid Man* Can't forget him. His tank moving arm pumping laser shooting ass is perminatly sketched into my brain. 

Culex from super mario rpg
Bowser from almost any mario game
Mike Tyson from Punch-Out
Gruntilda
Gary Oak
Brutus from Halo 2.... Just kidding

I don't think anything will ever beat Psycho Mantis from Metal Gear Solid.

NG2: Archfiend
Eternal Sonata: Frederick
Twin Snakes: Liquid

I'm surprised The End hasn't been mentioned yet, easily the most memorable boss fight for me, though not difficult or flashy himself the build up and atmosphere of the fight was so tense, and you can't forget being able to fast forward the internal clock and him dying through old age.

The final boss in Shadow of the Colossus (and the rest of that game pretty much)
Verdugo from RE4 (naturally)
The Giant from RE4
Kaptain K. Rool from Donkey Kong Country 2
Kaos from Donkey Kong Country 3
Bowser from Super Mario World
Bowser from Super Mario Bros 3
Bowser from Paper Mario (lol, more Bowser)
Yunalesca- Final Fantasy X
Seymour Flux- Final Fantasy X
Chairman Drek- Ratchet and Clank 1
Magician Type 0- The House of the Dead

"I'm surprised The End hasn't been mentioned yet, easily the most memorable boss fight for me, though not difficult or flashy himself the build up and atmosphere of the fight was so tense, and you can't forget being able to fast forward the internal clock and him dying through old age."

"Hmm, I really liked the fight against the End in MGS3, but I didn't really like the character."

50 Cent: Blood on the sand.

Final Fantasy V had some really memorable boss fights, mainly Gilgamesh during the batle at the big bridge and Galuf's showdown against Ex-Death. Seriously, going one on one against a mage that has FULL BODY ARMOUR and a goddamn sword, and isn't afraid to blast you with the strongest spells in the game, all while you're still fighting with like negative ten thousand billion HP until FINALLY, Ex-Death retreats and Galuf's efforts to save everyone results in his death.

Manly tears, GiantBomb. Manly tears.

Sephiroth - FF7
Yiazmat - FF12
Lavos - Chrono Trigger
Berial - DMC4 ( first time I saw him I was like WHOAH)
Jecht- FFX

"Off the top of my head:

The Great Mighty Poo

Ganon

Psycho Mantis

"

the Boss is my favorit Boss.
when the music starts playing half way trough, that just to epic.

Poo monster from Conkers lol

KOTOR1 vs Malak.

He was a pain in the ass, but a lot of fun and when you finally got him down, it was a great rush of satisfaction.