FFI: Garland (He's gonna knock you all down.)
FFII: The Emperor (Turns into some evil looking demon and shit like that.)
FFIII: Cloud of Darkness (Holy shit. Tits and snakes. It's like Medusa.)
FFIV: Golbez/Zeromus (Lunar people who will destroy this puny planet.)
FFV: Exdeath (His final form is a tree. Shit's so cash.)
FFVI: Kefka (Cool psycho clown who enslaves the world and doesnt afraid of anything.)
FFVII: Sephiroth (Summons meteors and has a beastly theme.)
FFVIII: Ultimecia/Edea (Evil sorceress who phases through time. Totally hawt.)
FFIX: Kuja (Pretty awesome guy who trances and has a tail. Also friends with a giant ball.)
FFX: Sin (Giant whale who goes around nuking cities and absorbing people.)