It is difficult to definitively answer the question of which SCP (Secure Containment Procedure) is invincible, as there are many SCPs with different levels of invulnerability. In general, the majority of SCPs are incredibly resilient to damage and many have some form of physical invulnerability.
For example, SCP-682 has a “regenerative trait” that makes it capable of recovering from nearly any amount of damage done to it, although it still can be affected by certain substances such as acid or certain types of energy.
SCP-2998 is a powerful entity which is described as being “so powerful that it is essentially an invincible force”. SCP-1000, more commonly known as “The Perfect organism” is also virtually invulnerable and can self-regenerate itself as long as it has access to a source of energy.
Additionally, SCP-106 is also highly resilient to damage and is supposedly indestructible.
However, while all these SCPs are highly resilient and possess certain traits that make them appear invulnerable, it is important to remember that they are not actually invincible. Most SCPs can still be affected by certain conditions or substances and can be neutralized or contain if the proper precautions are taken.
Is SCP-682 unkillable?
Not definitively, as SCP-682 has been terminated multiple times. The most recent attempt as of January 2020 was in SCP-682 Termination Log -452-2, which was successful. The body of SCP-682 was incinerated and all remnants were disposed of in the core of a neutron star.
However, SCP-682’s regenerative powers are extremely powerful, so much so that even if it is terminated, it will eventually come back. It is unknown exactly how long it takes for SCP-682 to regenerate, as its constantly changing state makes it difficult to measure.
It is theorized that it could take anywhere from a few days to centuries for SCP-682 to regenerate. Therefore, it could be argued that SCP-682 is unkillable in the long run, but is not entirely invincible.