Jeff the Killer was one of the most creepiest and mysterious photo online. It began in 2008 when a girl called Katy Robinson allegedly uploaded a photo of herself to 4chan. The overweight girl was immediately harassed and insulted by the board's users, resulting her to go offline.
A day later, another girl who claimed to be Katy's sister said that Katy has committed suicide as a result of cyber bullying.
Not long after her death, a character known as Jeff the Killer started appearing online. It started its online appearance on a 2.5-minute YouTube video under the name Sesseur. The short clip features a story about how Jeff accidentally spilled a bucket of acid while trying to clean a bathtub.
Jeff took the form a person with a white face, blank eyes and half-mad smile, Jeff quickly became an internet sensation. Then the cult of Jeff the Killer began: Jeff's photo became an inspiration of many horror stories including creepypasta, WikiAnswers and QuoteV. Dozens of YouTube users put their own version of Jeff, Lego has also reenact Jeff.
His pale face and eerie eyes has been recreated into many sorts of fanart on devianArt. A video game with the name Jeff the Killer has also been created.
4chan members began wondering who is actually Jeff the Killer is. The photo was clearly a Photoshop, but the reason is unknown. This was until a 4chan member discovered the early version of Jeff the Killer looked very similar to Katy Robinson. Speculation then concluded that a bully took Katy's image to be Photoshopped, making it look scary. Others said that it was a photo of a Photoshopped dog.
Another speculation said Jeff was probably a viral marketing effort done to promote the slasher film Saw V. To some, he is said to be similar to the Joker.
If either of those is true, Jeff's character is actually a joke. But the theory has never been confirmed.