Constantine EP Daniel Cerone told IGN that DC Comics character The Spectre might be coming to the show - as a way of further opening up DC's occult universe (and even possibly using the introduction to get The Spectre his own show). But as Cerone noted, this was all part of the early creative discussions about Constantine.
Well, now we can report that Jim Corrigan -- the character who later becomes The Spectre in the comics -- has been cast. Irish actor Emmett Scanlan (In the Flesh, The Fall, Guardians of the Galaxy) will play Corrigan, and will appear on Constantine as a recurring guest star.
On Constantine, Corrigan will be a homicide detective in New Orleans who is plunged into Constantine's world of occult horrors. Furthermore, Corrigan is someone who is obsessed with justice, and who doesn't let police procedure or red tape stop him from putting away the bad guys, even if the bad guys turn out to be inhuman.
Constantine will premiere on October 24th on NBC.