mehh, in ff7 the only person in ff7 he killed that made him look evil was aerith,
shinra people dont count, cuz you THE GOOD GUYS killed 50x more shinra people within the course of the game,
aerith was sephys only trophy kill in that game,
ultimecia, didnt kill anyone directly, shed possess people and have them kill people, (like when she released the monsters from the moon to the planet and wiped out that entire city) and in the end compressing time obliterating most life on the planet,
kefka, without hesitation destroyed most the planet, much like ultimecia, nearly putting humans into extinction, if it wasnt for him dresing like a gypsy id say he was the most evil dude,
kuja, bad guy?, in the end of the game him and zidane are talking as friends, he was no longer evil by the end of the game, he wasnt even the final boss, that fat lady thing was probably the only evil person in that game,. that odin attack scene pwned, (though i forget who it was that summoned bahamut when alexander and bahamut fought)
yu yevon?, pansy,...nuff said, seymour was teh evil dude in ff10,
jecgt?, see above
x death, well, wasnt he the dude who used mind control to control that guy, (i forget alot of stuf about ff2) then you had to go to the moon to face? well they sprung him on you too short, you didnt hear about him til wayyy too late in the game to be considered evil, id ay the biggest villain is yourself, when cecil fihts himself when becoming a paladin,