Carl Granville was the husband of Alice Cassity, who was oldest sibling of the Cassity family, who came into great wealth through dubious means.
Carl and Alice lived on her family's land in Shoshone, Idaho. Sam and Dean Winchester arrived there because they were in search of a hellhound to kill in order to satisfy the first of the Trials. They were fairly certain that since the family's wealth came from oil being struck on their land where no oil had ever been detected before, it was likely that a crossroads deal had been made by someone in the family. When Carl introduced himself to them, he happily described himself as the "trophy husband." They decided that Carl was not the one who would have made a demon deal.
Later, as Alice and Carl enjoyed a romantic candlelit dinner, they heard what they thought was a wolf howling in the distance. Alice left the table to check on her horses and Sam and Dean followed her, believing that she was the one who had sold her soul. Back at the dinner table, Carl was attacked and killed.
Sam later discovered that Alice was unaffected by Carl's gruesome death. She explained that even though they had both grown up in the area, she had scarcely even acknowledged him until Valentines Day 2003, when they had attended the same party and he seemed different. She had magically fallen in love with him, although she could not remember why. She said that they shared ten happy years together, but after he was gone she was not sad.
Later, as Ellie was explaining to Dean her deal with Crowley, she revealed that once Carl had gotten drunk and told her that he had summoned a demon and "did some kind of magic".