Guillerm March is an Spanish comic book artist and professional illustrator. He worked for Spanish Publisher Eros Comix on some of their adult comic books in 2000. His first published work for DC Comics was also his debut on the American comic book industry in 2008 on the title Joker's Asylum: Poison Ivy and later he worked on other titles including Batman, Detective Comics, Azrael: Death's Dark Knight, Oracle: The Cure, Gotham Gazette and Gotham City Sirens, which is probably the work for which he is most easily recognized.

Henri Scala is a French author, primarily incorporating his previous career as a National Police commissioner, which he held for over two decades, working primarily in investigative policing in Paris. His graphic novels explore the criminal underworld, the lives of those within it, and the experiences of those working to dismantle it.