Coulrophobia is no laughing matter. Although the actual phobia is somewhat rare, most people agree that clowns are creepy. Clowns as pranksters, jesters, jokers, harlequins, and mythologized tricksters have been around for ages, but when did they turn into the sinister beings that haunt our nightmares? This inherent creepiness was taken to an extreme with the idea of the ‘killer clown.” And some people believe this started with the arrest of infamous serial killer-John Wayne Gacy. Also known as "The Killer Clown", Gacy murdered 33 young men before burying them in his crawl space.
Sources:
-https://www.bbc.com/culture/article/20161019-a-surprising-history-of-the-bad-clown
-https://owlcation.com/humanities/History-of-the-Medieval-Jester