The Dover Demon is a monster (meaning it may or may not exist). It was first seen in Dover, Massachusetts by Bill Bartlett, on April 21, 1977. He had been driving in backroads, and saw it in the headlights. There were two people, in the back of the car, neither of whom saw it. Bill sped away from the scene, and returned later but did not see it. It was later seen by three other people, each of which did not confer with each other yet had similar stories.
The second person to see the Dover Demon was a fifteen year old boy who mistook the being as a small friend and chased after it, and after noticing that it was not the friend he was looking for, he was shaken, and told some authorities. The third and fourth witnesses were a couple who at first mistook it for a small animal (possibly a raccoon), but quickly realized it was not.
The Dover Demon was described as being four feet tail, hairless, having a thin neck and thin limbs, with nimble fingers, no discernible ears, a huge head, and pale peach skin. Its eyes glow alternating orange and green, and can easily navigate rocky terrain on all fours.
Its population size, eating habits, weight and where it came from are all unknown. However, many speculate that it is an alien, perhaps a gray. I further speculate that it may even be a child with extreme Opitz Trigonocephaly Syndrome, which would fit some of the characteristics (even though most people with Opitz-C still look remarkably, well, human, and the eyes would not glow the way the witnesses described; however, at maximum three of the witnesses saw the eyes, most likely only two or one. Also, most of the witnesses saw only fleeting glances from their car, and so they could be easily mistaken).
The Dover Demon was not described as dangerous, and is not known to possess any abnormal abilities, and was described by all the witnesses as timid.
Here is an ASCII art (I apologize in advance for its quality:
\ O O /
// \ \\
/|\ / /|\
Where these people hallucinating? Or is there really a Dover Demon?
This node was based off the article from The Field Guide to North American Monsters by W. Haden Blackman (book).