"You know, Dave," Chicago children's entertainer Pogo reportedly said over dinner with two cops who'd been tailing him, "clowns can get away with murder." Pogo would know, because outside of his clown identity he was John Wayne Gacy, the notorious 1970s serial killer and maybe one of the worst things to happen to clowns since the 1892 opera Pagliacci.

Clowns, it's fair to say, are not currently having the best time of it, PR-wise. The fourth season of American Horror Story, which debuted Wednesday, features Twisty the Clown as the primary antagonist: a terrifying perversion of the profession with a mask of grinning, oversized teeth and distorted black lips. In the opening episode, Twisty bounds up to a young couple in broad daylight, knocks them both out with juggling clubs, stabs the young man over and over again, kidnaps the woman and locks her up with a young boy in a decrepit old school bus, and forces them both to watch him craft balloon animals (there being clearly no limits to his malevolence).

In addition to this new incarnation of the monstrous, murdering clown trope, rogue scary clowns have been spotted recently stalking the streets of Wasco, California. In July, a "creepy" clown wearing a red wig and clutching a handful of pink balloons was sighted walking through Brooklyn's Green-Wood Cemetery. The professional clown industry, for once, isn't smiling. Membership of the World Clown Association, a U.S.-based trade group for performers, has fallen from 3,500 to 2,500 over the last 10 years. In the UK, a similar group, Clown International, has lost almost 90 percent of its members from its peak in the 1980s. Earlier this year, Butlin's holiday camp, in the popular destination of Bognor Regis, withdrew its annual offer to sponsor the group's annual gathering thanks to a decline in overall clown approval ratings.

How, exactly, did clowns go from lovable children's entertainers to the bewigged, bone-chilling incarnation of evil? The answer is complicated, and spans a period of almost 200 years, even if the current trend of coulrophobia seems to have peaked with the ascent of online media.

Traditionally clowns are anarchic figures who defy the boundaries of normal social conduct, even before Heath Ledger's Joker just wanted to watch the world burn. In Edgar Allan Poe's 1849 story Hop-Frog, a physically deformed court jester who's consistently the butt of practical jokes encourages the king and his court of noblemen to dress as orangutans covered in tar, at which point he sets them all on fire. The unpredictable nature of a clown's behavior, and his or her tendency to transgress acceptable standards of behavior (by, for example, throwing pies in each others' faces, or squirting water on an innocent bystander with a trick buttonhole flower), probably makes us wary of what other lines they might cross.

The makeup, too, is a factor. Traditional clown face paint—a white base, with exaggerated red lips and cheeks—was pioneered by Joseph Grimaldi, a popular entertainer in the early 19th century, and can be manipulated to create a face that is either grinning in an absurd rictus or tragicomically sad. "At its roots, clownaphobia springs from the duplicity implied by the frozen grins and false gaiety of clowns," writes cultural critic Mark Dery in his 1999 book The Pyrotechnic Insanitarium: America on the Brink. "The clown persona protests too much; its transparent artificiality constantly directs our attention to what's behind the mask." The frozen smile of a clown makes his or her true expression impossible to read—yet another factor that leads us to ponder whether or not they can be trusted.

Despite all this, clowns were typically viewed in a positive light for most of the 19th and 20th centuries, even though Leoncavallo's aforementioned 1892 opera, Pagliacci, told the story of a clown who murders his unfaithful wife and her lover with a knife. (Se il viso è pallido, è di vergogna, the clown sings, or, If my face is white, it is for shame.) The turning point, culture-wise, appears to have been the arrest of Gacy, dubbed "the Killer Clown" by the media, whose grisly string of sexual assaults and murders contrasted so vividly with his alternate clown persona. As Pogo, Gacy performed at parades, parties, and charitable events, even meeting First Lady Rosalynn Carter in 1978 thanks to his role as director of Chicago's Polish Constitution Day Parade. While on death row, he painted a number of portraits of clowns, many depicting himself as Pogo, claiming that he wanted to use the paintings "to bring joy into people's lives."

The national shockwave following the exposure of one of the most prolific serial killers in American history may have forever traumatized the country as far as clowns were concerned. In 1980, Gacy was sentenced to death. Two years later, Tobe Hooper and Steven Spielberg released Poltergeist, a movie in which evil forces terrorize a household, in part by bringing young Robbie's Clown Doll to life and having it pull him under his bed and attempt to throttle him to death. In 1986, Stephen King published IT, a horror novel about the murderous Pennywise the Clown, who stalks children, terrifying them and occasionally ripping off their limbs. In 2009, King talked about the idea for Pennywise with Conan O'Brien. "As a kid, going to the circus, it'd be like 12 full-grown people piling out of a little car, their faces were dead-white, their mouths were red, as though they were full of blood," he said. "They were all screaming, their eyes were huge: What's not to like?"

Pennywise, as played so memorably by Tim Curry in the 1990 television movie of IT, emerged shortly after Jack Nicholson's Joker in Tim Burton's 1989 movie, Batman. The Joker, at least in comic books, has always seemed to occupy an odd space between jester, clown, and harlequin, but Nicholson's depiction felt deliberately clown-like, both in his pockets full of tricks (the flower filled with acid instead of water), and the way he used poison gas to give his victims pallid white skin and distorted scarlet smirks. Ledger's Joker, coming almost two decades later in Christopher Nolan's The Dark Knight, was more explicitly wearing surreal makeup to enhance his scarred Chelsea grin: less Bozo, and more Insane Clown Posse.

Can clowns be saved? At this point, given their popularity as fright masks, the rise of coulrophobia, and the decline of the wholesome, apple-pie birthday party, it’s hard to see a future for clown acts outside of the circus (which itself is suffering thanks to the impossible dominance of the global juggernaut that is Cirque du Soleil). There is some hope: Even though studies in the past have typically shown that children fear clowns, research conducted at Tel Aviv University this year found that children undergoing allergy testing were less anxious when a clown was present in the room. Maybe the future for clowns is less about Ronald McDonald (nothing’s scarier than diabetes, after all) and more about distracting nervous patients from the giant needles injecting allergens into their skin.