They may not make good antagonists by themselves, but I've got a couple ideas from this, nonetheless.
Cultish hive mind that recruits Innocents and tinkers with their minds. They'd make good sleeper agents because they won't remember why they carried out their tasks, only that the impulse struck them.
Every User in my setting has a UID, and with certain forbidden Authority functions, a User can be stripped of their ID, functionally becoming a Process. Naturally, Innocents would make for good targets, and there are Daemons and Process who crave the privilege of User immortality.