Per 
Item #: SCP-173
Object Class: Euclid
Special Containment Procedures: Item SCP-173 is to be kept in a locked container at all times. When personnel must enter SCP-173's container, no fewer than 3 may enter at any time and the door is to be relocked behind them. At all times, two persons must maintain direct eye contact with SCP-173 until all personnel have vacated and relocked the container.
Description: Moved to Site-19 1993. Origin is as of yet unknown. It is constructed from concrete and rebar with traces of Krylon brand spray paint. SCP-173 is animate and extremely hostile. The object cannot move while within a direct line of sight. Line of sight must not be broken at any time with SCP-173. Personnel assigned to enter container are instructed to alert one another before blinking. Object is reported to attack by snapping the neck at the base of the skull, or by strangulation. In the event of an attack, personnel are to observe Class 4 hazardous object containment procedures.
Personnel report sounds of scraping stone originating from within the container when no one is present inside. This is considered normal, and any change in this behaviour should be reported to the acting HMCL supervisor on duty.
The reddish brown substance on the floor is a combination of feces and blood. Origin of these materials is unknown. The enclosure must be cleaned on a bi-weekly basis.
Addendum 173-1: On ██/██/████, personnel near SCP-173's containment chamber reported strange lightning strike-like noises being heard in the chamber instead of usual stone-scraping sounds. The HMCL supervisor that was on duty at the time was contacted about this, and went to check on SCP-173's containment chamber through the surveillance footage. In the camera feed was nothing but bright flashing lights making it impossible to see what was going on inside SCP-173's containment chamber. After █ hours passed, the flashing lights stopped and inside SCP-173's containment chamber was nothing different. The room stayed the same and SCP-173 showed no signs of any change whatsoever.
Addendum 173-2: After the incident regarding the bright flashing lights occurring in the containment chamber of SCP-173, testing was authorized by Site Director, ████████. Three Class-D subjects were ordered to enter SCP-173's chamber and explain to the researchers on their radio any differences prior to the flashing lights inside 173's containment. As soon as the three subjects entered SCP-173's containment cell, all of them described having a feeling of "severe fatigue and anxiety" when observing the SCP. Regardless of their current state, the test-subjects were ordered to approach SCP-173 and tell the researchers if there is anything on SCP-173 that might've changed. With Subject D-5654 and Subject D-2344 observing SCP-173, Subject D-8796 was ordered to touch SCP-173 and describe what he felt. This was D-8796's response:
"This fucking thing feels like it's made out of…armor..or something. I don't know, man. This is something I've never felt before. It's so rough and thick. And its face, it looks…fleshy..like it's alive. Yuck!"
Subject D-8796 was then ordered to touch SCP-173's face.
"Jesus fucking Christ! It's all so slimy and wet, this is disgusting! Oh, oh my god. What the fuck?!"
The researchers then asked what made D-8796 suddenly alert.
"His smile just turned into a frown! I don't like this. I don't fucking like this at all."
Subject D-8796 was then ordered to stop touching SCP-173 and all three test-subjects were then told to leave the room.
Addendum 173-3: As soon as the three test subjects left the chamber, everyone in the vicinity of SCP-173 went blind for a few seconds and when few personnel were able to see again, they saw that SCP-173 already killed the majority of everyone that was in the room, including the three test subjects. SCP-173 was declared to have breached containment and all personnel at the Site were notified to go to the nearest breach shelter through the site announcement system; Three Mobile Task Force Units were called in to recontain SCP-173 and were deployed at the Site, but as soon as they arrived at SCP-173's location, they described feeling very anxious, weak, and tired. And then seconds later, their vision went completely pitch black and all three units were killed, but not all three died in the same way as the other. For the first unit that died, SCP-173 snapped his neck. For the second unit, SCP-173 performed strangulation and then proceeded to slice the neck. Finally, for the third unit, SCP-173 completely mutilated the task force unit by ripping his arms and legs and then his head, one by one; MTF Unit Epsilon-10 designated "See No Evil" was deployed at the Site and arrived to SCP-173's location. SCP-173 was contained successfully.
Addendum 173-4: After the ██████████ incident, SCP-173 has shown new characteristics that were not originally revealed until June ██/██. SCP-173 was relocated to Site-███
Revised Object Class: Keter
Revised Description: An ancient god known as the "Koitern", SCP-173 is a vaguely humanoid entity that is constructed of an unknown material that is abnormally durable and is invulnerable to any source of damage, no matter what the damage is and how strong it may be. It has 4 eyes, with the 2 upper eyes being green and the 2 lower eyes being pitch black; the green eyes that exist on SCP-173’s face will glow in pure darkness. Its facial organs are made of a strange organic tissue. Randomly, its mouth will change from a smile to a frown. There exists a type of rash on the back of SCP-173 that seems to resemble ashes of some sort. SCP-173 is animate and extremely hostile and attacks by snapping the neck at the base of the skull, by strangulation, or by completely shredding the victim to pieces but cannot move when in direct line of sight. However, when a being that is observing SCP-173 doesn’t have eyes or has the ability to resist blinking, SCP-173 will then either summon new eyes for the viewer and/or will completely remove the inability to blink.
When observing SCP-173 whether it be directly or through video recording, the viewer will feel intense anxiety and severe fatigue. SCP-173 has also been known to bypass the resistance of anything that tries to prevent its cognitive hazards, and has been known to be invulnerable to/annihilate omnipotent entities and remove their abilities, regardless of how powerful they are.
Addendum 173-5: After being revealed to have a true form which is seemingly omnipotent and the imminence of SCP-3812 causing a CK-Class Reality-Ending Scenario, SCP-173 was introduced to SCP-3812. As soon as SCP-3812 noticed SCP-173, it was about to remove SCP-173 from existence and researchers were getting ready to reclassify SCP-173 as neutralized, but what happened next shocked them. SCP-3812 was found dead on the floor in his African-American form with his blood covered in SCP-173’s hands.
SCP-3812 was then reclassified to neutralized
Addendum 173-6: An attempt to terminate SCP-682, SCP-173 was introduced into SCP-682’s containment chamber. SCP-682 makes several screeching noises, and quickly presses against the wall farthest from SCP-173 staring at it. Due to the cognitohazardous abilities that SCP-173 possesses, SCP-682 felt weak and tired, and could not stare at SCP-173 for long and had to blink, causing SCP-173 to snap SCP-682’s neck. To the personnel’s surprise, SCP-682 came back to life but became extremely terrified of SCP-173 and begged the researchers to take SCP-173 out of its cell.
Addendum 173-7: Out of curiosity to see how SCP-173 would react, SCP-999 was introduced into SCP-173’s containment chamber. SCP-999 then spotted SCP-173, but did not feel the negative effects that SCP-173 usually causes. SCP-999 then approached SCP-173 making cooing gurgling sounds and then proceeded to hug SCP-173. SCP-999 then backed off and went away from SCP-173, much happier than usual.
