Apollyon

Used for SCPs that are impossible to contain, or are about to irrevocably break containment. An SCP with this class will inevitably end the world. The classification was first used in SCP-927 on the Editthis wiki in 2008; it essentially meant that the SCP was a particularly dangerous keter. The original iteration of the Apollyon class did not appear in any additional SCPs, and was ultimately removed from SCP-927 by September of 2008. The class did not appear again until 2014, when it was used in SCP-2317. Dr. Clef, the author of 2317, did not intend for Apollyon to be a serious object class. Rather, the class was meant to indicate that the SCP article was abnormal, and that the documentation was something hidden even from most of the SCP Foundation. Dr. Clef came to regret re-creating the Apollyon class, and removed it from SCP-2317 in March of 2018. Despite Clef's misgivings, Apollyon has had a heavy influence on the SCP writing community. The class is used in SCP-3999 and S.D. Locke’s Proposal (an entry in the SCP-001 hub), both of which were created for the SCP-3000 contest. The class is also referenced in SCP-3148 (A2032), SCP-3799, SCP-3301 and SCP-3557. Following the removal of Apollyon from 2317, the class was used in SCP-4005 and SCP-4057 (both of which were SCP-4000 entries), Jim North's Proposal (an SCP-001 proposal), SCP-4023, SCP-4780, Meta Ike Proposal (an 001 proposal), SCP-4547, SCP-010-INT and SCP-5618.

During the SCP-5000 contest of January-February 2020, five additional Apollyon SCPs were posted. These SCPs were 5000:Evolution Revolution (since deleted), SCP-5500, SCP-5678, SCP-5055, and SCP-5321.

Following the 5000 contest, the class was used in SCP-5939, SCP-5092, SCP-5799, SCP-5391, SCP-3955, McDoctorate's Proposal (main article), SCP-4273, SCP-5157, and SCP-5956 (main article).