please suggest me a book with a very gentle villain, despite them being absolutely despicable

i really want to read something with a villain who is gentle, polite, and or soft-spoken. BUT i do not want them to be sympathetic. maybe someone who is so powerful/confident that they don’t feel the need to exert themselves. or maybe someone who is just incredibly pragmatic. i want something quietly menacing. scary in the most amiable way possible. also NOT a love interest.

i don’t particularly care about genre, but i am partial to sci fi.