The tagline for this series is "The demons he fights aren't just his own".
The character of John Constantine was created by British writer Alan Moore and artist Steve Bissette. He deputed in the pages of Saga of the Swamp Thing #37 in 1985, and soon branched off into his own ongoing comic series Hellblazer, which ran for three-hundred issues from 1988 to 2013.
The Constantine TV series is actually the second live-action iteration of the character. A Constantine feature film directed by Francis Lawrence and starring Keanu Reeves was released in 2005.
The series halted production on Constantine following its initial thirteen episode run. At the time, the future of the program remained in contention. 
In April, 2015, the website Buzzfeed issued a premature article announcing the show's cancellation, but the story was quickly recalled, leaving fans to speculate as to whether or not they would see their British bad boy again. 
On May 11th, 2015, the official notice of Constantines cancellation was announced. 
NBC policies restricts the use of casuals visually smoking in their programs. Although John Constantine is portrayed as a smoker, there is never a seen where he is ever shown actually exhaling cigarette smoke.