Blame this. Because I sure do.
Screaming Death Killbot 6000
It’s three feet tall, made of mirror-smooth and polished flexible steel that somehow never shows any sort of seam or joint. It has a roughly humanoid face, with two alarmingly large glowing eyes and a LCD ‘mouth’ that flashes when it ‘laughs,’ which the Screaming Death Killbot 6000 does often — typically when it’s killing its prey. The hands and feet all end in alarming-looking blades that shock, stab, serrate at high speed, or otherwise inflict prodigious amounts of blood and pain. And it talks just the way, while using just the dementedly-cheerful child’s voice, that you’d expect from something called the ‘Screaming Death Killbot 6000.’
It also has an invariably-accurate alignment detector. Simply put, the Screaming Death Killbot 6000 can detect ‘Evil’ creatures in its presence, with apparently no exceptions. Even more significantly, you cannot make a Screaming Death Killbot 6000 falsely detect someone as being Evil, either. Evil things die screaming under its spinning, merciless fingers; Good (or even Neutral) ones have absolutely nothing to fear. A Screaming Death Killbot 6000 will not even attempt to protect itself from attacks made by non-Evil people.
They’re technically self-aware entities, but conversing with a Screaming Death Killbot 6000 is always an alarming activity. This is partially because they’re not much for small talk, but it’s mostly because they’re murder machines that insist on discussing — in great and graphic detail — just how much they enjoy their work. They’re not exceedingly smart, and you can destroy one if you work at it hard enough, but they’re also fairly nastily determined and seem to have limited self-repair abilities.
Also; if you are being attacked by one, people are going to assume that you deserved it, because you are Evil. The definition of ‘Evil’ will depend on the campaign, of course, but this creature concept explicitly draws from D&D’s alignment system: you need to have done something generally very bad, and enjoyed doing it, to get the attention of one of these things. Interestingly, under those alignment guidelines a Screaming Death Killbot 6000 itself registers as being firmly Lawful Evil; it seems to enjoy the reaction that it engenders in Good people, but is so obedient to the rules of its existence that it won’t even try to evade them. Nobody’s ever been able to get two Screaming Death Killbot 6000s within eyeshot of each other, so nobody knows what would happen if two did.
Nobody also knows where Screaming Death Killbot 6000s come from, but a lot of people believe that they’re created by the forces of Hell as a subtle attack on the public perception (and very concept) of Good. Which would explain why certain avatars of Good destroy the things on sight. After all, just because you’re supposed to Smite the wicked doesn’t mean that you get to giggle while you do it…