1) Albedo (Xenosaga)
2) Xemnas (Kingdom Hearts II)
3) Voldemort (Harry Potter)
4) Darth Sidious/ The Emperor (Star Wars)
5) Psycho Mantis (Metal Gear Solid)
6) Magneto (X-Men)
7) Vergil (Devil May Cry 3)
8) Magus (Chrono Trigger -- he was a villain for a while, so I hope he counts)
9) Killer (Shadow Hearts: From the New World)
10) Byakuya Kuchiki (Bleach -- another "for a while," also hope it counts)


Edit: Snap, Dynast made me realize all mine are male >_>.