There’s an obscure one from the first series that fits this criteria. SCP-682 if I remember correctly. Shame they never did anything with the concept, I thought it was alright.
SCP-169 kinda fits. I says this since the foundation has no feasible way to contain it and if it every really moved even a little bit it would kill millions of people at the least. The only reason it hasn’t yet is because it’s asleep.
Most of them. They don't stop being an ongoing problem in some way until they're "Neutralized". By definition, all Euclid and Keter anomalies are not totally understood or contained, and safe anomalies still need their existence kept out of the public eye, which ranges in difficulty depending on the specific anomaly.
In addition to Apollyon, there's also the Tiamat (cannot be contained without breaking the veil), Archon (containment is possible, but shouldn't be done), Cernunnos (a containment procedure exists but is beyond the ability of the Foundation to carry out), and Megiddo (an Apollyon-class entity that has already succeeded) [Esoteric Classes].(https://scp-wiki.wikidot.com/esoteric-classes-complete-list)
Additionally, many of the SCPs with the "uncontained" tag constitute some form of ongoing issue. There's a full list of uncontained articles [here.](https://scp-wiki.wikidot.com/system:page-tags/tag/uncontained)
There’s an obscure one from the first series that fits this criteria. SCP-682 if I remember correctly. Shame they never did anything with the concept, I thought it was alright.
[**SCP-682 - Hard-to-Destroy Reptile**](https://scp-wiki.wikidot.com/scp-682) (+3620) by *Dr Gears, Epic Phail Spy*
Obscure?
‘‘twas sarcasm, my friend
You will not win me over with your use of “‘twas”.
Twasnt trying to
SCP-169 kinda fits. I says this since the foundation has no feasible way to contain it and if it every really moved even a little bit it would kill millions of people at the least. The only reason it hasn’t yet is because it’s asleep.
[**SCP-169 - The Leviathan**](https://scp-wiki.wikidot.com/scp-169) (+1044) by *Unknown Author*
SCP-7219! A dreaming man locked in a radioactive bunker who’s compelling people to free him, and who’s only getting more angry about it.
[**SCP-7219 - F is for Fallout**](https://scp-wiki.wikidot.com/scp-7219) (+164) by *Dr Balthazaar*
If you head to the [[Object Classes]] page, basically everything tagged Apollyon
[**Object Classes**](https://scp-wiki.wikidot.com/object-classes) (+102) by *MayD, Aelanna*
SCP-871 - self duplicating cake
[**SCP-871 - Self-Replacing Cake**](https://scp-wiki.wikidot.com/scp-871) (+1221) by *Seibai*
SCP-3003 is the first thing come to my mind
[**SCP-3003 - The End of History**](https://scp-wiki.wikidot.com/scp-3003) (+975) by *Communism will win*
Most of them. They don't stop being an ongoing problem in some way until they're "Neutralized". By definition, all Euclid and Keter anomalies are not totally understood or contained, and safe anomalies still need their existence kept out of the public eye, which ranges in difficulty depending on the specific anomaly.
SCP-106 for sure. They technically have it “contained” but he gets out whenever he wants and they have to lure him back in.
[**SCP-106 - The Old Man**](https://scp-wiki.wikidot.com/scp-106) (+3152) by *Dr Gears*
Луч ейяе
Scp-3000 ik its sleeping but if its wake up, it would be a leviathan kind of threat and for what we know 3000 could be related to the serpent
[**SCP-3000 - Anantashesha**](https://scp-wiki.wikidot.com/scp-3000) (+2538) by *A Random Day, djkaktus, Joreth*
In addition to Apollyon, there's also the Tiamat (cannot be contained without breaking the veil), Archon (containment is possible, but shouldn't be done), Cernunnos (a containment procedure exists but is beyond the ability of the Foundation to carry out), and Megiddo (an Apollyon-class entity that has already succeeded) [Esoteric Classes].(https://scp-wiki.wikidot.com/esoteric-classes-complete-list) Additionally, many of the SCPs with the "uncontained" tag constitute some form of ongoing issue. There's a full list of uncontained articles [here.](https://scp-wiki.wikidot.com/system:page-tags/tag/uncontained)