Spoiler for like, any book existing.
I think mine has to be the villain in Mirror Man. Idk, he wasn’t intimidating, he wasn’t interesting. He was meh.
Also the villains from The Chain. Dear God they weren’t sympathetic in the slightest. The book tries to act like they were atleast pitiful but FROM THEIR INCEPTION, they were just evil assholes who enjoyed causing pain. The book itself wasn’t all that great anyways.
Julia from Seveneves. Utterly selfish, out of her league, and uses her one skill to corrupt and ruin things for everyone else.
Since you mentioned Stephenson, Ala from Anathem. How could she have a Liaison with his best friend immediately after getting evoked 😥
Someone else that enjoyed that book in the wild? Unusual.