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CASSIECAT2.jpg Anyalsis Complete. New behaviors detected.

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Appearance F1 Menu Art

Reinforced Concrete (Passive)

Heavy Armor level bullet resistance.
Higher penetration weapons are more effective.

Tantrum (Active)

A pool of filth on the ground that slows targets. Regain a small amount of HS when stained targets are killed.

Blink (Active)

Teleport to a marker on the ground, forcing everyone to blink. Will kill the nearest human if they are in range.

Break Neck Speeds (Active)

SCP-173 moves a lot faster and can blink further, but is unable to kill.

CATSTATUS.png Health: 3000
CATSHIELD.png Hume Shield: 1200
173EyeBloodshot.png Blink Time: 3.6s
CATSPRINT.png Speed:
Normal: 7.5 m/s 

10 hubes

Break Neck: 12.8 m/s 

17 hubes

Other Information
Spawn Location: Light Containment Zone
Weakness: Can't move when looked at, Micro H.I.D.
Nickname: Matthew
Class ID: 0
Class Color: #EC2222
Article Link: Page

SCP-173 is one of the seven playable SCP classes in SCP: Secret Laboratory.
SCP-173 acts as an assassin class SCP, meant to quickly hunt down and eliminate a single target or small groups of players.

In Game[edit]

At the start of a round, SCP-173 will spawn in its Containment Cell in Light Containment Zone.
Upon spawning, SCP-173 won't be able to exit the cell right away, as the only exit (a gate) is locked shut, which gives the Class-Ds and Scientists some time to explore. After a short amount of time, the gate will automatically open, and SCP-173 can leave its cell, free to roam around the map.

When SCP-173 isn't being observed, they can press Left Click.png Left Click on a player to snap their neck.
Once seen, SCP-173 stops moving, but starts a 3.6 second countdown for their Blink ability. When the cooldown ends, the player can hold Right Click.png Right Click to mark a location. When the player releases Right Click.png Right Click, SCP-173 will teleport to their mark, which will force humans to blink. If any humans are in range, SCP-173 will automatically kill the closest one. The max range for Blink is 9.375 meters.

The countdown is shown in the center of SCP-173's screen over a symbol of an eye. When Blink is ready, the eye turns red, and SCP-173 can blink (only if seen). If no one looks at SCP-173, the red eye shrinks over time. If SCP-173 is seen again before the eye disappears, it will become full, and 173 can blink immediately.
The red eye lasts 3 seconds, starting when all witnesses are lost, but only appears after the countdown finishes.

SCP-173 also has several abilities it can use:
Breakneck Speeds can be turned on by pressing Shift, and can be used whether or not SCP-173 is seen.
In this state, SCP-173 moves 1.7x faster, blinks 1.8x further, charges blinks twice as quickly, but is unable to kill players. This mode ends when the player presses Shift again, though the player must wait at least 1.5 seconds after activation. It will also ends automatically 10 seconds after SCP-173 is spotted.
The ability has a 40 second cooldown starting when the ability ends.

Tantrum can be activated by pressing the F key.
When activated, SCP-173 will leave a pool of filth on the ground. Players entering the pool gain the Stained Reduces player speed by 20%
Players cannot sprint
Status Effect, which lasts until the player leaves the pool. Even after leaving the filth, the Stained effect lasts for two more seconds. If SCP-173 kills someone while they are under the effects, they will instantly gain back 100 Hume Shield. Each pool of filth lasts for 180 seconds, and multiple pools can be placed down. Tesla Gates will destroy nearby filth when activated.
Tantrum can only be used when SCP-173 is not seen, and has a 30 second cooldown once used.

SCP-173 has bullet resistance similar to SCP-106, but unlike SCP-106, the bullet resistance isn't as high, and the damage taken is based on the penetration of the weapon. Weapons with lower penetration will deal less damage than weapons with higher penetration. SCP-173 has an armor value of 80%, which is equal to Heavy Armor.
SCP-173's Hume Shield does not factor in this bullet resistance, and will take normal damage.

SCP-173 can talk to the other SCPs by holding down the Q key. This voice chat can be heard by all SCPs no matter the distance.

Related Achievements[edit]

  • Dying to SCP-173 grants the Is this your first time? achievement.


Sight Stingers
Chase Ambient
Attack Sounds
Ability SFX



  • SCP-173 doesn't have a ragdoll upon death, and instead falls apart into pieces when killed.
  • Dying to SCP-173 will cause the player's head to be twisted 180 degrees around the base of the neck.
  • SCP-173 was the first class added to SCP: Secret Laboratory and the oldest part of the game that still exists today.
  • SCP-173's ability icons were designed by RiriLeTiroir.
  • SCP-173's v11.2.0 Tantrum sound was recorded by Northwood Studios Audio Manager Brendan "Scot" O'Dowd, who recorded it by putting his microphone in a beanbag and shaking it.