Craig Thursten was a student living in Richardson, Texas who accidentally created the Tulpa Mordechai Murdoch with his cousin Dana, in Hell House.
Season 1
Craig looked like he was in his late teen years. He, along with his cousin Dana, found an abandoned house, drew symbols all over the walls and spread the legend that it was called "Hell House" and that a certain Mordechai Murdoch used to live there in the early 20th century. The story stipulates that Mordechai, having no money to feed his numerous daughters, hanged them one after the other in the cellar.
Due to the story spreading all over the internet, the supposed ghost materialized as many people began to believe in it. Sam and Dean later got him to spill the beans about his involvement in the spreading of the legend.