SCP-106

 - The Old Man is a Keter-class SCP in Series I, originally created by. SCP-106 was among the earliest SCPs written after the "Mass Edit" on the SCP Wiki; and is one of the most iconic SCP monsters, due to making appearances in multiple Tales and SCP video games.

The titular subject of SCP-106 (also known by his nickname "The Old Man") is a humanoid entity who resembles the rotting corpse of an elderly man. SCP-106 has the ability to produce a corrosive mucus that melts through almost any substance, and can phase through any surface by opening portals to a pocket dimension. The Old Man is a cunning and sadistic predator that actively hunts down humans (preferably aged 10-25), with the intention of dragging them into his pocket dimension to slowly torture them to death. He has proven to be a nightmarish challenge for the Foundation to keep contained; due to his corrosive mucus, teleportation abilities, and invulnerability against most physical harm, which allow him to regularly escape from his cell to go on killing sprees against any nearby personnel.

Also see

 * The Young Man
 * SCP-3001