In 1518 the city of Strasbourg suffered the first case of the Dancing Plague, a collective mania where hundreds of people took to the streets and danced until they collapsed. Survivors often mentioned seeing a “demon” dancing with them, which became known in German as Milchsblut.
The last known case of the Dancing Plague was in 1937 in the village of Skyline, Alabama. What started as a regular festival quickly turned into a frantic dance hysteria. A photographer, also afflicted, managed to take a few pictures of the event.
Sources: Original creature created by Trevor Henderson for Mike Diva and the band Milkblood (video). 3D model provided by Mike Diva. Pictures from Library of Congress, original drawing by Pieter Brueghel.