Mimic

The Mimic is a monster invented by Dungeons & Dragons and which has become famous throughout /tg/ and beyond. In contrast to its close kin, the rust monster and the owlbear, the Mimic is not remembered for being a goofy idea, but for its sheer deadliness, which has seen it readily adapted in /v/ media.

The mimic has its roots in Old School Roleplaying, most specifically the tendency for such games to boil down to a sadistic DM out for blood vs. a bunch of paranoid players. Something like a slime with a hard shell instead of a gelatinous membrane, the mimic is an amorphous predator that disguises itself as inanimate objects in order to lure potential meals close, then attack. Most iconically, they take the form of treasure chests, making them one of the most recognizable of "gotcha!" monsters.

To further the paranoia, the mimic has often been portrayed as having more advanced shapeshifting than that; Advanced Dungeons & Dragons gives them the Greater Mimic (big enough to pretend to be entire rooms) and the Househunter Mimic (big enough to pretend to be whole houses), whilst 4th edition states that in their adult forms, mimics can disguise themselves as human beings and walk amongst them to find prey.

What few except real grognards remember is that, originally, the AD&D mimic came in two forms; the regular mimic, whilst still a hungry predator, was quite intelligent (Int 8-10, so about as smart as your average human being), capable of speech, and more than willing to bargain in exchange for food (and not that fussy; enemy corpses, spare trail rations, they'll eat it). The more iconic modern depiction of the mimic comes from the variety AD&D labeled the Killer Mimic, identical in every way except that it was tougher and far stupider (Int 2-4, so only animal intelligence), meaning it just attacked whatever food it could find.

The connection between Househunter Mimics and the Gazebo meme remains unclear.