Jack Rowand / The CW
Killer: Billy Grimm, played by Robert Knepper, is the leader of the cult.
Modus operandi: So who is in the cult? They are rabid fans of a thriller TV show titled "The Cult," who are inclined to re-create the crimes they see depicted on the show.
Still at large? Yes, but Matt Davis, pictured with Jessica Lucas, is an investigative journalist who is looking into his brother's disappearance and finds out about other mysterious disappearances involving the cult.