He's the Hellblazer -- DC Comics' occult detective and magician, John Constantine. He’s been a key player in the supernatural world of DC and Vertigo for almost 30 years, and now he’s finally getting his own show on NBC. So let’s take a look back at the strange history of Constantine, both within the DC Universe, and without. Here’s everything you need to know about Constantine! Spoilers from the comics follow... The Saga of the Swamp Thing #37Continue reading…