A Grue (Gruesomicius ravenousi) is a box-shaped gap-toothed mammal known for eating humans, though more recently they have been known to kill certain lone wolves, construction workers, a gerbil or two, speranah, the occasional monkey, people who send annoying chain e-mails, your pets, and...well, Grues like eating a lot of things. Grues are not often seen roaming the wilderness in herds, whistling old-time Irish pub songs, working on crossword puzzles, and calculating the amount of back taxes owed by car salesmen. The reason Grues are not often seen doing anything is because grues live in total darkness, so the whole "seeing" thing would be kind of hard to do. The likelihood of being eaten by a grue is probably non-zero.
It is widely believed that all emeralds are grue, but in fact, all emeralds are bleen.
There are an estimated 47 grues left in the United States today due to the Grue conservation program - luckily all grues are kept under heavy rocks, or locked away in abandoned biker bars. Of course, being creatures of darkness that tend to eat anything they can get within range of, these numbers are likely inaccurate, outdated, or simply made up by the same people who tell us that pretty much everything causes cancer.
The game of Zork consists entirely of being repeatedly eaten by a grue. (more...)