Clark Adams is the main antagonist of the episode Long-Distance Call of Supernatural.
Sam and Dean investigate some deaths that are related to strange phone calls, where calls from people claim to be spirits of the deceased. And when Dean answers a phone call believing to be John Winchester. And during the investigation, they soon come across Clark who is a supervisor, and due to the deaths and events, the Winchesters think he is a Crocotta. Sam suspect it's Stewie, and arrests him. However Clark appears and hits Sam in the head, and then kills Stewie. Clark then makes a phone for Dean pretending to be his father and manipulates him so much, and a father who thought his son was murdered. However, Sam breaks free and pushes Clark to a piece of metal that comes out of the wall killing him.