John Constantine was created by writer Alan Moore, with contributions from Steve Bissette and John Totleben. The character first appeared in the comic book "Swamp Thing".
Constantine received his own comic book series titled "Hellblazer" published by DC Comics under its Vertigo imprint.
The character's iconic appearance, including his trench coat, blond hair, and cynical demeanor, was solidified during the early issues of "Hellblazer" by artist John Ridgeway and others.
John Constantine was portrayed by Keanu Reeves in the feature film "Constantine," which brought mainstream attention to the character outside of comics.
The character was integrated into the main DC Universe with a new ongoing series titled "Constantine: The Hellblazer" as part of the DC Rebirth initiative.