There are multiple ways for parahumans, non-humans or groups to be labeled a class-S threat. High-level duplicators and villains who operate to any exponential degree are automatically considered S-class if their powers generate more instances of power generation or recurring effect in an epidemic pattern. A tinker with the ability to create true AI would apparently be counted as an S-class threat.
Three PRT Thinkers must all rate a situation sufficiently highly before it can be considered an S-class situation.
Being labelled a class-S threat is equivalent to receiving a kill order, in addition to which the PRT calls everyone they can to destroy the threat. According to Miss Militia, the difference in response to a class A crisis and a class S one is minor. Some tertiary protocols change, the Triumvirate are guaranteed to assist, and there are penalties for anyone who subscribed to the critical situation roster if they sit it out.
There were epidemic protocols for dealing with a Class S situation.
One of Dragon's responsibilities was monitoring the known S-class threats for changes or other incidents. She developed a program to predict the patterns of their attacks, which she sent to Armsmaster; using this program, the two were able to predict Leviathan's attack on Brockton Bay and give forces some time to gather beforehand.
Furthermore, Ash Beast had the potential of being an S-class threat but moved slowly enough to be avoidable.Blasto had a "high risk" of becoming S-class.The Number Man referenced the Three Blasphemies as a force on par with Sleeper, the Slaughterhouse Nine, and the Ash Beast, but they were not among the established S-class threats listed in discussion prior to the Echidna incident.
Most threats outside of North America were believed to be destroyed in Gold Morning.
There were threats of a similar level that were not widely known and were dealt with by organizations such as the Thanda. Or contained in PRT Quarantine Sites.
Other class S threads that would appear over the course of Ward include:
↑ 1.01.1To be clear, the self-reproducing creations thing is what gets you labeled as a Class-S threat. That's basically a kill order, but more in the line of "We're going to call in everyone we can to put you down." - Wildbow on MythWeavers
↑Take stock. Who didn’t I have? I didn’t have Contessa, who I couldn’t see. I didn’t have the Blasphemies, who hadn’t even registered to me because they weren’t human, even if they had powers, I didn’t have Sleeper and… - Excerpt from Speck 30.5
↑Keep in mind that S-class threats can include groups, as it does with the S9. - Wildbow on Reddit
↑The self-recursive thing is a definition of an S-class threat, but not the definition. - Wildbow on Reddit
↑“We’re talking class-S, even if you ignore pre-situation verification. Section nine-seven-five, article fifty-seven. Classifying high level duplicators and villains who operate to any exponential degree. Nilbog and Simurgh both count, and Noelle does too. If the powers generate more instances of power generation or recurring effect in an epidemic pattern…” - Exerpt from Queen 18.4
↑Shower: You’re sure they’re not AI? Heart_Shaped_Pupil: If they were A.I. I could be a potential S-class threat. Heart_Shaped_Pupil: I’m just really lame Heart_Shaped_Pupil: it’s hobby programming. Not my focus or specialty. - Excerpt from Glow-worm P.7
↑“Bullshit,” Tattletale said. “S-class. I know Appraiser offered a purple-velvet diagnosis for his previous ratings on Endbringer attacks, so that’s not the reason it’s so low. Eleven’s score of eight has to be above the seventy-five percent mark, and an answer as vague as Hunch’s is going to be a seventy-five percent exact, as per section nine-seven-six, article seventy-one. That’s three values that have to be above the threshold for declaring a threat level S situation.” - Exerpt from Queen 18.4
↑“I don’t know why we’re even discussing this, when you seem to have our operations manual memorized and you’re capable of realizing it for yourself,” Miss Militia said, “but it doesn’t bear dwelling on. The difference in our response to a class A crisis and a class S one is minor at best. Some tertiary protocols change, we won’t necessarily have Alexandria, Legend or Eidolon assisting, and there’s no penalties for anyone who subscribed to the critical situation roster if they sit this one out.” - Excerpt from Queen 18.4
↑“If the heroes aren’t showing in full force, others won’t either.” Tattletale said, “And there’s no epidemic protocols with a class-A.” - Excerpt from Queen 18.4
↑She might have devoted more attention to the subject, but she was already falling behind. She moved on to her other responsibilities. The Class S threats. - Excerpt from Interlude 10.5
↑“Dragon. That program you gave me, predicting the patterns of class S threats, remember it? I made a few modifications, to see if I couldn’t catch any highlights, I’m running a dozen of them concurrently. One, I called HS203. I want you to look directly at this. I’ve put it behind some pretty heavy security, but if you wait a second, I’ll-”
“I’m already looking over it,” Dragon interrupted. “I see what you did. Linking my data to atmospheric shifts. I think I see it.” - Excerpt from Interlude 7
↑ 12.012.112.212.312.4There’s six class S threats active in the world at large. The Endbringers make up three of them. The Slaughterhouse Nine as a group are a fourth. - Exerpt from Queen 18.3
↑ 13.013.1Week I had clearance, I watched all the video we have of the class S threats. Leviathan, Simurgh, Behemoth, Slaughterhouse Nine, Nilbog, Sleeper. - Exerpt from Queen 18.4
↑I reached out to Ash Beast, a living force of nature. It had originally triggered in Matruh, Egypt, and had been roaming since, making its way across Africa. All of the destructive power of any class S threat, tempered by the fact that it usually traveled on foot, and people could see it coming from miles away. When it reached a settlement, that settlement was usually evacuated. - Excerpt from Speck 30.5
↑Note: High risk of Class-S classification. Should creations self-propagate, kill orders are pre-authorized. - Excerpt from Interlude 19.x
↑“No,” the Number Man said, and he managed to sound only a little condescending. “I’m saying that parahumans as a whole are chain reactions waiting to happen, and we were already approaching a critical point. Every year, the percentage of parahumans in the population increases. At that same time, the odds of a cataclysmic event happening somewhere are increasing steadily. Imagine a situation like the Echidna event that turned out more unfavorably, or a Nilbog who wasn’t content to stay in one place. We have the blasphemies, Sleeper, and the Ash Beast, even the Slaughterhouse Nine, all as living examples of this concept at work. The world already stood on a precipice, and I’m not even mentioning the Endbringers in all of this.” - Excerpt from Extinction 27.2
↑“That’s about it, for North American quarantines. A lot of the unquarantined Class-S threats died in the fight against Scion. Uh.”
I could have elaborated on motivations, but I felt like that might have spoiled our little hero-villain truce here.
“Yeah,” Tattletale said. “Intentional, I think. As much as anything was, then.”
I had so many frigging questions on that subject, but… no. Again, it would have spoiled things.
Khepri had let them die while fighting Scion. Tattletale agreed with the hypothesis. - Excerpt from Sundown 17.8
↑[The Thanda fight] the class-S threats that aren't so obvious as Sleeper, Nilbog or the Blasphemies, and the villains who don't take the spotlight. [...] Perhaps it would be better to say Class-S level? Not necessarily known & classified, but arguably as dangerous in their own right? - Wildbow on Spacebattles
↑Trickster - Line of sight, swaps everyone and everything, comingles swapped matter - person + mailbox = two mashed together abominations of flesh and mailbox, slowly dying as organs fail. PRT van + PRT van = two mashed together heaps of metal with people crushed inside, very possibly setting fire or exploding given friction of metal on metal and leaking gasoline. Size/mass/density sense that normally allows Trickster to gauge how swappable things are is extended to give knowledge of everyone and everything within a one-mile radius. Reflexes amped up. Effectively navigates a battlefield by swapping himself instantly and repeatedly, mapping out routes in advance, leaving mangled destruction in his wake, flanking and hiding. - Wildbow on Reddit