There's no shame in being afraid of monsters.

Who wouldn't quail at the thought of a sudden tete-a-tete with Bigfoot or a brush from the wing of a giant, flying reptile? Most people, though, believe these mysterious creatures exist only in nightmares or horror movies--until they spy a nine-foot tall, shaggy beast sprinting through their own yard or must swerve to avoid hitting a bat-winged, human-sized thing taking dead aim at their windshield.

Unlikely as it may sound, a surprising number of credible, sober citizens of all ages and from every walk of life say they have encountered unknown creatures in parks, fields, lakes, highways and, yes, urban areas all over the Americas.

As a former newspaper writer, I've been collecting and investigating such reports ever since my 1992 story "The Beast of Bray Road" about sightings of a werewolf-like creature in southeastern Wisconsin. I believed then that the witnesses were sincere, and I still believe the great majority of those who have contacted me since are doing their best to describe the indescribable.

Some beasts seem more monstrous than others -- I'd sooner meet a merman than a Chupacabras -- but all exhibit fearsome features. I've called out seven apex terrifiers from American Monsters (Tarcher, $16.95):

Batsquatch

With furry, humanoid bodies, glowing red eyes and bat-wings wider than a pickup truck, they seem to enjoy swooping at passing vehicles and pedestrians. Reports are most numerous in the northwestern US, but Batsquatch has been spied in rural Wisconsin, West Virginia, Pennsylvania and even downtown Chicago. Some researchers believe it's an unknown, giant bat species, others have suggested its fly-bys are out-of-time appearances of a Sumerian demon-god named Pazuzu.

The Flathead Lake Monster

One of the busiest lake monsters in America, the 20-30 foot long creature that many say inhabits this 188-square mile Montana lake has made at least 102 appearances between 1899 and 2013. With a large, horse-like head and a row of undulating humps leaving a wake behind it, the giant eel-like creature has brushed up against swimmers and lurked near stranded boats. Two have been spotted together, so perhaps they are breeding!

Goatman

Some say they're heinous genetic experiments gone wrong, others believe they're forest spirits similar to ancient Greek satyrs or the old nature god, Pan. The horns, hooves and upright posture, however, are likely to conjure the word "devil" in the minds of contemporary witnesses. Many urban legends claim that the goatmen guard old roadways and even snack on unwary travelers (goats, after all, are said to eat anything). Although they're sighted in all parts of the country, one of the most famous of these Billy Goat Gruff legends comes from St. George's County, Maryland, where let's just say it's unforgivably unkind to stray pets.

Ear-Eater of Jasper County

Sometimes, the scariest creatures are the ones you don't see. An unseen monster terrorized citizens of Jasper County, Mississippi during a few tense weeks in 1977 as it preyed on their pork population. Whatever it was, it had jaws formidable enough to bite the head off a 50-pound hog. It also tried to decapitate a 300-pound sow but only managed to tear its ears away. The thing still effectively raided nine different farms. It left large canine tracks and was never caught, although one of a pack of smaller, feral dogs that accompanied or trailed it was shot by a sheriff's deputy. Where the ear eater went next is unknown.

Wampus Cat

Also dubbed the Doberman-lynx or dog-cat by various witnesses, this creature resembles a huge, unholy hybrid of canine and feline characteristics. People have reported being stalked by these creatures in the canyons around Los Angeles and in some states in southeastern U.S. A supporting Native American legend of a woman cursed for spying on a men's council meeting hints at mythic origins of these creatures. The woman was doomed to roam in the shape of a human-like, great cat and, according to the legends, still haunts many southern forests.

Sasquatch

Perhaps the best known of the world's "unknown" creatures, many eyewitnesses are loathe to call them monsters since they appear so human-like and seem to confine most of their aggression to throwing rocks and snapping branches. But their sheer size (often eight feet tall and weighing 500 pounds or more), evident intelligence and amazing ability to elude capture or camera can scare the bejabbers out of those who somehow provoke the creature's aggressive side. In a human vs Sasquatch cage fight, there's little question as to who would come out on top.

Gator Man

Maybe it's just our instinctive mammalian response to things with scales and gaping jaws, but fear of reptiles is a common human trait. Up the ante with a man-sized gator that stands upright and stealthily shadows the eyewitness (a la the croc that trailed Captain Hook in Peter Pan), and you have a beast that pushes all kinds of fear buttons, physical and psychological. Such a creature lurks in the St. John's River in eastern Florida, according to one eyewitness, who still wonders why he was "chosen."

It's that eerie, inordinate interest the beasts show in humankind that I find most disturbing in these accounts. And although many people tell me that they're eager to spot a monster themselves, quite a few witnesses wish that they hadn't, and that they could unsee it. The creatures, in the meantime, seem content to leave us wondering whether they're some elusive part of the natural world or an Otherworldly puzzle that will never be solved.