"Crimson Wanderer is a mysterious warrior of outstanding strength and skill, feared for his deadly power, but is also seen as a hero by many. He's widely considered as one of the most dangerous humanoid entities in The Backrooms that racked one of the highest kill count ever recorded.
There's conflicting accounts regarding the appearance of the Crimson Wanderer, suggesting that different individuals perceived them differently. Initially, this is thought to be caused by an illusion, but further evidence proved that the Crimson Wanderer has actually multiple forms. He's not to be considered as a shape-shifter, and his transformation is apparently part of his power. See the next section for the details of his forms.
The default form of the Crimson Wanderer is an over 2 meters tall knight in a fantastic metal armor, complete with an old, worn-out red cape. He carries a claymore that he keeps on his back, but he often drags it across the floor, causing a loud, scratching noises while he approach his target. Considering his heavy movement, it's estimated that his weight, complete with his armor and weapon, is about half a metric ton.
Currently, it's uncertain what the Crimson Wanderer looks like under the armor. A popular theory suggested that the Crimson Wanderer is nothing but a sentient armor, so there's no body inside. This theory is unlikely to be true, considering the evidence that the Crimson Wanderer does bleed whenever they get hurt. Many believed that the entity was once an ordinary wanderer, but somehow got corrupted, cursed, consumed by his own power, or by some other malevolent forces. Even then, his semblance of humanity and personality still remained.
There's many theories regarding the connection of the Crimson Wanderer and the Crimson Heart from the Treasures of the Void, but there's no concrete evidence of the theories so far." -Backrooms Wiki