The poll is over, thank you everyone for your suggestions and for voting!
Vanessa which means 'butterfly' which is a graceful and unassuming name on the surface; but it also sounds like it could belong to one of those 'dignity laugh' villainesses from 90s anime. But if that's not the villainess vibe you're going for, then there's still the appeal to give a sweet-sounding name to a more serious, ruthless-leaning villainess too.