Series creator Clyde Phillips and editor Perri Frank tell IndieWire how they keep their serial killer drama fresh after 20 years of horror. When the Showtime series “ Dexter ” premiered in the fall of 2006, it introduced a new kind of anti-hero to television: a serial killer ( Michael C. Hall ) driven by horrific impulses that he tried to put to a positive use by targeting violent criminals. Although Tony Soprano had opened the door for morally ambiguous protagonists on “The Sopranos,” and “Mad