Thinman is a fictional character from the American television series Supernatural inspired by the Slender Man myth, as evidenced by his origin story, appearance, and supposed abilities. His first and only appearance in the series was the episode #THINMAN.
Thinman was an internet meme/urban legend created by Ed Zeddmore, one of the members of a group of paranormal investigators called Ghostfacers, in order to prevent Harry Spangler from leaving the team. Ed created Thinman by taking an old photo of a butler and altering it into the infamous creature with photoshop and posted the photo anonymously on a horror forum. Ed only meant for Thinman to be one case for the Ghostfacers to chase down, but it quickly took on a life of its own and became a crowd sourced legend.
In the urban legend, Thinman lurks in the background of his intended victims' lives, occasionally being caught in the background of a photograph, until he is ready to kill them. The Thinman's victims can range from the old to the young, to male or female. However people cannot agree on what Thinman actually is, as the lore centered around him changes from blog to blog.
The Thinman's real life existence first becomes apparent after a girl named Casey Miles is murdered in her bedroom. The evidence as to who murdered her pointed to the Thinman due to the selfie she took of herself minutes before she died, showing Thinman standing behind her. The picture was uploaded to a Thinman fan forum immediately afterwards and the news of this mysterious death brought the main Sam and Dean Winchester to Springdale, Washington under the assumption that the being was a ghost. During the course of their investigation, the Winchesters meet up with Ed and Harry, who were not searching for Thinman at the time.
Shortly after the Winchester's arrival in Springdale, another Thinman murder occurs. This time the murder is caught on the security cameras at Johnny's Apple Country Diner, where the manager is shown to have his throat cut open by Thinman, who appears to teleport from the parking lot to the inside of the locked diner.
At this point Ed thinks Sam and Dean should take over the case, as they are far more experienced, but Harry wants to try and hunt down Thinman. Harry refuses to listen to his partner's advice and forces Ed to drop him off by some woods. Meanwhile, Ed visits the Winchesters at the motel they are staying at and tells them the truth about Thinman's origins. Dean accuses Ed of creating a real life version of the Thinman in the form of a Tulpa and Sam insists that Ed tell Harry the truth because secrets ruin relationships.
During his hunt, Harry comes face to face with Thinman who slashes him in his abdomen. However, Harry manages to survive his encounter through sheer luck and even gets the opportunity to kick Thinman in the groin before he makes his escape. Sam, Dean, and Ed come to his rescue, and discover tire tracks which the Winchesters think may belong to whoever is pretending to be Thinman. Ed finally tells Harry the truth, which results in Harry becoming extremely mad at him and no longer being able to trust him.
The Winchesters decided to follow the tire track lead, and are followed by Harry and Ed once they decide that they will work together in order to fix the mess Ed created. The tire tracks lead to a warehouse, where the Winchesters are tasered by Tom Norwood, the deputy of Springdale's sheriff whom Sam and Dean went to for help while investigating the Thinman case. Norwood reveals that he and his friend Roger, a local busboy, are the ones responsible for the Thinman murders and were motivated by their shared desire to make the Thinman a reality after it became apparent that blogging wasn't enough for them. Roger, disguised as Thinman, steps up to cut Dean's throat while Norwood records the act in order to ensure that the legend will continue.
A frantic Sam works to pick the lock of his handcuffs so that he can save Dean. However, a noise distracts Norwood and Roger who go to investigate. Ed and Harry trap "Thinman" but are quickly captured by Norwood. When they return to where Sam and Dean were cuffed, they see that Winchesters have escaped. The boys attack Norwood and Roger, Dean kills Roger, and Norwood pulls a gun on Sam and Harry, only to be shot by Ed. With the "visionaries" behind the Thinman murders dead, the legend was finally put to rest.