The Jeff Killer Jumpscare originated on YouTube, where a series of eerie, glitchy videos began circulating, featuring a distorted, green-tinted figure with a grotesque, maniacal grin. The character, dubbed "Jeff Killer," would suddenly appear on screen, accompanied by a blood-curdling scream, sending viewers into a state of panic. The initial videos, uploaded by an anonymous user, quickly gained traction, and the legend of Jeff Killer began to spread.