Mimic (D&D)

Mimics are a type of monster from the famous Dungeons & Dragons multiverse, they are famous for being ambush predators and opportunistic killers - thus are often used as a living trap by dungeon-masters, often utilizing the curiosity or greed of adventurers against them in order to cause a sudden and sometimes fatal encounter.

History
Mimics are shape-shifters who are prone to take the guise of treasure chests so as to lure nearby adventurers within their grasping range - at which point the monster reveals itself and attacks via both grabbing at a victim and trying to devour them with a massive mouth, Mimics can be found anywhere an adventurer is likely to run into treasure : such as old crypts, abandoned tunnels and so forth.

The origins of Mimics lay in wizards who originally created them as a means to defend their treasure from thieves - unfortunately the magic didn't work as planned and as such the Mimics are now largely left to their own devices, even those still under the care of a wizard often have a less than pleasant relationship with their creator.

Traits
Mimics come in two varieties, a smaller and more intelligent common Mimic and a larger, less intelligent Killer Mimic - common Mimics are Neutral in alignment while the Killer Mimics are Neutral Evil.

All Mimics are carnivorous in nature and thus will devour anything they can capture, including sapient humanoids - common Mimics are capable of limited speech (a corruption of the same speech used by the wizards that created them) but Killer Mimics are incapable of any spech.

Common Mimics are intelligent and will gladly offer information in exchange for food but Killer Mimics will attack no matter what, even if attempts are made to communicate.

When attacking a Mimic will cover itself in a glue-like substance that quickly fastens anything that comes in contact with it in place, alcohol can disperse this glue and if a Mimic dies the glue will eventually dissolve : Mimics can also neutralize the glue at any time they please.

In addition to this Mimics are immune to the acid of most slimes, oozes and puddings - they are solitary in nature and avoid sunlight, making them the definition of a dungeon-dweller.

Subtypes
while traditional Mimics almost always favor the form of treasure chests there are a rare and powerful subtype that instead take the guise of houses or even entire castles - luring unsuspecting victims inside before trying to devour them, these especially large and dangerous mimics are known as a House Hunter.
 * http://www.mojobob.com/roleplay/monstrousmanual/m/mimihohu.html

Trivia

 * Mimics are one of Dungeons & Dragons most iconic monsters, similar to the Beholder, as such Mimics are used extensively in many campaigns and are also now a regular stock character in many fantasy works.
 * Mimics are a unique monster that is not based directly on any real world mythology or folklore.