Hidebehind
The hidebehind (Cryptopsthenis sp.) is one of various species of small mammalian creatures that are always behind the viewer and therefore cannot be seen directly.
The smallest species of the genus (Cryptopsthenis maculatus) routinely inhabits underground environments like subway tunnels, sewers, and crawl spaces, and is a threat only to insects, shrews, and other lifeforms smaller than the average mouse. Many creatures in the average subway or cave would be able to eat this type of hidebehind if they wanted to or could catch one. However, the creature's surprising ability to somehow always be behind any other creature hunting it makes the hidebehind too much trouble for most predators in its environment to bother with. Additionally, this species of Cryptopsthenis packs an emotional "punch" far out of proportion to the diminutive size of its members. Individuals of most species of Cryptopsthenis are able to broadcast a feeling of threat, but C. maculatus's broadcast is so strong that it easily drives away smaller predators like cats, and can make even much larger lifeforms (like human beings) feel creepily as if they're being stalked. Rats seem to have some resistance to this effect, making them the species which most often seeks out hidebehinds for food.
Other hidebehind species (C. dimorphulum, C. nondescriptis) are more aggressive in the protection of their territories and hunting grounds, and have occasionally been implicated in human deaths -- though it's hard to accurately assign blame in these situations, as no one has been able to see or describe the attacker. The wolverine-sized C. silvestris palinensis apparently favors woodland ecologies and was frequently mentioned in the folklore of nineteenth-century lumberjacks: but there have been no verified sightings since the introduction of the chain saw, lending some credence to the theory that these creatures prefer the quietest ecologies available. (SYWTBAW)
(See also: Subterranean ecologies; Wizardly fauna (North America).)