Around the first of every year (or the end of the one preceding it), Mothman usually turns up on many of the various Fortean "Top Ten" lists, ranking hither and yon as people's favorite monstrosity of one category or another. For me, Mothman is most likely representative of various cryptozoological phenomenon, though many proponents of the legends also state belief that the dark-winged-one could have been any number of other things: an alien being, perhaps, or even some interdimensional presence.
The beginnings of the legend are well known, centering around Point Pleasant, West Virginia in November of 1966 when a group of frightened youths came barging into the local police station telling about a terrifying encounter they'd had earlier in the evening on November 15. Thus a blue-blooded American legend was born... but was the creature in question really what so many others have described over the years: a winged man-thing?
Indeed, there are a number of reports of strange creatures that were being seen in Point Pleasant around the time of the so-called "Mothman flap." The majority of the accounts seem to indicate the presence of a large, winged entity that's generally described as being close to six or seven feet tall, with large red eyes oriented near the chest area of an average human form. Curiously, the size of the wings themselves are often described as being too small to be capable of providing lift for a creature so large... but perhaps even more strange are the aspects of the Mothman mythos that may involve a creature with no wings at all!
I'm sure many folks just did a double-take, but bear with me here, because delving into the heart of the Mothman mystery should also be afforded an honest cross-examination of many of the claims made by those who encountered the creature throughout the late 1960s. Going back to those initial accounts around November of 1966, specifically the first one involving the two couples Roger and Linda Scarberry, and Steve and Mary Mallette, what is remembered of the encounter versus what was initially recorded does present a few discrepancies. For instance, when the story of the foursome's startling encounter appeared the following morning in the Pacific Stars and Stripes newspaper, a particularly odd statement was made about the creature's locomotion: that it "was an awkward runner."
Indeed, many familiar with the legend will recall that as the group sped along in their escape from the old World War II munitions area outside of town, the creature was said to have pursued them, flying along at incredible speeds matching that of the witnesses in their car. However, it is curious that this initial statement that appeared in print mentioned terrestrial locomotion of the bipedal variety, and in the absence of references to there being wings observed. The story would change greatly in subsequent recollections by witnesses, with famous statements such as, "That bird kept right up with us," furthering the creature's legendary abilities.
Later encounters, such as that of Marcella Bennett a few nights after the Scarberry/Mallette encounter, involved seeing the creature moving about on the ground, although again, no mention of wings or the creature taking flight was recorded. Even John Keel, who authored the first authoritative text on what might have been occurring in Point Pleasant around the time (having been there throughout much of the Mothman flap himself), would eventually begin to surmise that "Mothman" was more likely to have been the result a combination of different factors. While many of the encounters detailed what was obviously some kind of large bird, others seemed more indicative of a large, red-eyed humanoid, or what Keel referred to as an "Abominable Swamp Slob" (i.e. a Bigfoot-like creature).
While a majority of the misinterpretation regarding Mothman stemmed from the years surrounding its presence in Point Pleasant between 1966 and '67, certain aspects of the mystery have carried over into subsequent decades just as well. One popular myth that arose from the more metaphysical aspects of the Mothman story suggested that similar creatures were seen at the times of (or directly preceding) major disasters. Even stories regarding the terrible accident at the Chernobyl nuclear facility in 1986, as well as stories surrounding the Galveston Hurricane of 1900, began to incorporate tales of a "winged creature" that ominously appeared prior to each disaster. However, commenting at The Gralien Report in 2010, cryptozoologist and Fortean scholar Loren Coleman touched on the folkloric aspects of these stories as well:
John Keel and I openly discussed with the media, and did our best to straighten out the record regarding the mythos that became the Chernobyl “Mothman” accounts.
The Chernobyl story, the Galveston Hurricane-Mothman tie-in, and other examples given in the 2002 movie were pure fiction. As you note, right after the movie was released, various websites posted the Chernobyl/Mothman sightings as factual. But there is not one thread of evidence that any winged weirdies were witnessed before the Chernobyl accident.
It is a bit of movie fiction that has, unfortunately, moved into pseudo-factoid cryptozoology.
Indeed, to share Coleman's wisely-stated sentiments, what might be called "pseudo-factoid cryptozoology" could comprise far more of the Mothman mystery than many are willing to accept. A careful cross-examination of available data suggests that rather than one singular phenomenon having occurred in West Virginia between 1966-67, there were perhaps a multitude of strange happenings, which became compounded over the years courtesy of speculation and hearsay. These resulted in all-encompassing legends of a mystery beast we know today as "Mothman" (which, as most will admit, didn't even resemble a moth in the very best witness descriptions).
Whatever was really going on may be lost to time... but the mystery continues to captivate us; despite how some of the facts may have been changed with time.