Sometimes I dream about that red space, tucked away in some part of some city, in the back of some warehouse. And I can see what's been left in there and I can see why it can never be let out. And I wake up and I know it's all true.
~ The caption for the original picture of the Man in the Red Room.
The Man in the Red Room, also known as the Thing in the Red Space and the Fungal Person, is a monster made by the Canadian horror artist, Trevor Henderson. As the name implies, it's trapped in a red space/room.
The Man in the Red Room has appeared only once, on a post made by Trevor Henderson. Whoever is the narrator says that he again had a dream about “the red space”, tucked away in a part of an unknown city, in the back of a warehouse. He sees what's been left in there and knows why it can never be let out, hinting that the creature is a villain. Then, he wakes up, knowing it's all true. The picture shows the Man in his titular red room. It appears to be some thin monstrosity that is hanging upside-down from the ceiling. It has many holes in its body and its head is oriented right-side up, with a small piece of its body floating beneath its head to act as some sort of jaw. Interestingly, it appears that the creature’s hands and feet are in the ceiling, as they are not visible in the image, implying that he can pass through walls. The caption implies that the Man in the Red Room is somehow imprisoned there.
In internet folklore, a Red Room is believed to be a place where criminals take victims to be tortured and killed on the Dark Web as part of a snuff film (like most urban legends, it is very questionable how many of these truly exist and they are largely considered a kind of internet ghost-story): the Man in the Red Room may be referencing this legend.
Overall, the Man in the Red Room has no clear moral agency and has no goals whatsoever. It is possible it wants to escape the room to cause trouble to the real world, if not possibly murder people. The caption of its post suggests that it is imprisoned in its red space for a reason, one that the narrator has recognized through his dream.
On the other hand, it could possibly have a sympathetic background or even just wants to be let out for unknown reasons. Regardless, it has no clear moral agency, though the caption stating that the Man can never be let out suggests that he is villainous and a threat.
So far, the Man in the Red Room is the only villain in the Trevor Henderson Mythos to get some form of comeuppance, being imprisoned in a red room. The rest of the other villains in the mythos get none and are continuing to stalk on humanity to this day (at least as of now).