First Villain I ever played

Ini Miney from Ace Attorney!

might as well list others

including folks who while not outright villains definitely go into morally gray areas

also from Ace Attorney is Aura Blackquill

and I've always wanted to give Dahlia a shot but I know I could never ever, ever, ever do her justice

I played Eruka Frog from Soul Eater

an AU version of The Condesce from Homestuck

still wholly a villain

Rocma from Funamusea

....I feel like there have been at least two more from my earliest days cause I know Ini wasn't the f---oh right Kikyo

from Inu Yasha

I think I did some 2003 Sloth RPing way back in the days of Gaia too