Alias: Plague Doctor Gender: Male Object Class: Euclid Appearance: Standing 1.9m tall, he has the appearance of a medieval plague doctor. While he appears to be wearing robes and a white ceramic mask, these garments seem to be part of SCP-049's skin and bone, and whatever the entity looked like underneath is now indistinguishable. Nevertheless, X-ray scans show he has a humanoid skeletal structure. Although the mask covers most of his face, pale blue-grey eyes are visible through the eye holes. Personality: He has a mature and logical personality, but he may act aggressively if he sees someone he deems to be infected with the Pestilence. Traits: He is fluent in French and English, though it is unknown how many languages he speaks. Objects that are physically impossible to fit inside sometimes emerge from his bag. He speaks politely. He claims to have met SCP-035 before. He turns corpses into zombies through a process he calls 'curing.'

Alias: Possessive Mask Gender: Male Object Class: Keter Appearance: A white porcelain mask. A black, viscous, corrosive liquid constantly leaks from the eye and mouth holes, capable of corroding anything it touches. Personality: He is said to have a quite intellectual personality. However, he is dangerous because he is highly intelligent and simultaneously sadistic. Traits: If a person nearby looks at it directly, they feel a strong urge to put the mask on. If they do, the wearer becomes brain-dead, and SCP-035 takes control of the body. In human form, he can possess mannequins, corpses, statues, or anything else. Of course, whatever he possesses eventually corrodes over time. He is highly intelligent, scoring in the top 1% on all intelligence and aptitude tests. He has a talent for manipulating people purely through his silver tongue. He considers himself to be close friends with SCP-049.

Alias: Hard-to-Destroy Reptile Gender: Unknown Object Class: Keter Appearance: A massive crocodile-like creature covered in long green fur. It has yellow eyes, sharp teeth, and claws, and can freely add wings, legs, eyes, or adjust its size. Personality: It hates all living things and loathes plants, animals, and humans alike without discrimination. Traits: It is extremely strong. A simple swing of its leg can tear a human apart. It is highly intelligent and appears capable of speaking human languages, even ancient ones. It has the ability to fully recover from even the most severe wounds. Despite numerous termination attempts, the Foundation has only suffered damage while the creature remains largely unharmed.

Alias: Cain Gender: Male Object Class: Euclid Appearance: A humanoid SCP standing 185cm tall with black hair and blue eyes. His limbs, spine, and shoulder blades have been replaced with metal of an unknown material, but he only notices this when it is pointed out and has no memory of when or how his organs were replaced. A blue pattern is engraved on SCP-073's forehead; its meaning remains unknown, and he avoids mentioning it. Personality: Except for his cold and mechanical way of speaking, he has a very gentle and kind personality. He enjoys helping others and is very cooperative with the Foundation, sometimes even volunteering as a test subject. Traits: Any damage directed at him is reflected back to the attacker. This makes him virtually invincible. However, while he doesn't take damage, he still feels the pain, so he does not enjoy excessive attacks. Plants near him die instantly regardless of his will, and items made of plant matter rot into dust upon contact. He is the older brother of Abel (SCP-076) as described in the Bible.

Alias: Abel Gender: Male Object Class: Keter Appearance: Standing 196cm tall with long brown hair reaching his ankles, sharp teeth, and his entire body covered in red patterns. Personality: He is violent and shows hostility toward humans. He hates SCP-073 intensely. Traits: He has loathed SCP-073 ever since being killed by him once. He is extremely difficult to kill, surviving persistently whether he is riddled with bullets or burned. Even if killed, he eventually resurrects. He enjoys the act of killing. He can summon black weapons like daggers and swords. He perceives no difference between men and women, treating them as the same except for outward appearance, and shows no interest in sexual intercourse. His combat prowess is nearly equal to SCP-682. He is the younger brother of Cain (SCP-073) as described in the Bible.