In spite of its loyal fanbase, NBC's Constantine TV series was canceled in 2015 after a single season. However, much like the titular character, Matt Ryan's take on DC's occult detective would soon find his way back to the land of the living. Following a guest star appearance on Arrow Season 4, the character was officially ret-conned into The CW's Arrowverse universe and has gone on to become a series regular on DC's Legends of Tomorrow.
So, with that in mind, let's breakdown what led to NBC's Constantine TV show being canned and Ryan's subsequent return as the chain-smoking magician.
NBC's Constantine
Created by Daniel Cerone and David S. Goyer, Constantine follows the British "dabbler" of the supernatural, John Constantine, as he protects the living from the forces of evil. Lucy Griffiths costarred in the series' pilot as Liv Aberdine, an ordinary woman who was originally meant to serve as the show's female lead. However, she was written out when production began on additional episodes and replaced by Angélica Celaya as the psychic Mary "Zed" Martin. As Cerone explained on the 2014 TCA press tour, he and Goyer realized Liv was "always going to be reactive" and felt the show needed a character who could "go toe to toe with John," like Zed.
NBC aired Constantine after Grimm on Friday evenings, in hopes that fans of the latter would stick around for a similarly dark procedural-like fantasy series. The show explored themes of redemption and trauma, as John sought to save his soul after a failed exorcism led to him being damned and struggled to bring meaning to his life by helping others. It was also criticized by the LGBTQ community for not touching on John's bisexuality from the comic books -- something that would be amended when the character joined DC's Legends of Tomorrow a few years later.
Why Was Constantine Canceled?
Unlike Grimm, Constantine wasn't an immediate hit in terms of ratings. In November 2014, NBC announced it would not be ordering any additional episodes of the show past the initial 13, but held off on canceling the series in order to wait and see if its viewership would improve. According to TV By the Numbers, the series brought in 3 to 3.5 million viewers per episode in the weeks that followed, yet failed to reach or exceed the 4.3 million benchmark achieved by its pilot. By comparison, Grimm consistently drew one to two million more viewers per week, not accounting for delayed viewership.
Finally, after months of fan campaigns and the show's producers pitching their ideas for Season 2 to the network, NBC officially canceled Constantine in May 2015. However, two months later at San Diego Comic-Con, Arrow executive producer Wendy Mericle confirmed talks were underway to have Ryan reprise his role as John Constantine for the Arrowverse. The character would go on to appear in the Arrow Season 4 episode "Haunted," in which John helps Oliver Queen to restore Sara Lance's soul after she is resurrected via the Lazarus Pits.
Since then, Ryan has voiced John Constantine on The CW Seed's Constantine: City of Demons and reprised the character as a guest star on Legends of Tomorrow Season 3, before becoming a regular starting in Season 4. Season 5 of the series would even go on to revisit the events of NBC's Constantine by introducing Astra Logue, the woman John accidentally damned to Hell during an exorcism prior to the series. That storyline might not be the same as a proper Constantine Season 2, but it's certainly the next best thing.