1. Kefka Palazzo - Final Fantasy VI
Alias: Cefca Palazzo (Japanese version), Lord Kefka, The Psycho Clown, Master Kefka
Occupation: Court mage, magitek knight prototype, supreme God of magic(late in the game), Founder and leader of the Cult of Kefka
Powers: Magic, and developed absolute godlike powers that allowed him to destroy everything late in the game
2. # - Final Fantasy VII
3. Bowser - Super Mario Bros Franchise
Bowser doesn't have any grandiose plans of world domination, His whole thing is just kidnapping Princess Peach and getting some tail, Most of the time.
4. Ganondorf/Ganon - Legend of Zelda: Ocarina of Time.
5. Nemesis - Resident Evil 3: Nemesis
AKA: Nemesis-T Type (Pursuer) - Resident Evil: The Umbrella Chronicles
6. The Joker - Batman: Arkham Asylum, Various other Batman games.
7. Luca Blight - Suikoden 2
Although not the end boss (He dies pretty early in the game) He is the main protagonist, And is the most memorable (and evil) villain in the whole series.
The boss fist is also epic, And Blight dies in spectacular fashion!
8.The Archdemon - Dragon Age: Origins
AKA: Urthemiel, the Dragon of Beauty(Before the old God was corrupted)
9. Ultimecia - Final Fantasy VIII
10. Psycho Mantis - Metal Gear Solid
This nasty boss is the one who actually broke the fourth wall and actually read your damn memory card.
He would taunt you about your number of saves and mention other Konomi games you had saved. He also messed with your controller, inverting the game controls and other frustrating things.
He also wasn't the final boss in Metal Gear, But is one of the most memorable bosses ever!
He also had one of the creepiest character voices ever, And things got really creepy once he pulled of the gas mask. Near invulnerable unless you figure out to unplug you controller and plugging it into the second player port to prevent him from 'reading your mind'.
11. Tyrant - Resident Evil
Just when you thought you were a master of Resident Evil, The tyrant came along and b*tch slapped you back to reality.
You have to save all your magnum rounds, And anything else you could to have a chance. If you could do enough damage before getting your head taking off by the claw hand from hell, Barry will show up and toss you a rocket launcher to finish the job.
It is possible that the tyrant will dodge the rocket and kill you anyway, Though.
12. Donkey Kong - Donkey Kong
I't ain't on till it's on like Donkey Kong!