It sounds as if John Constantine could be making his way onto Netflix, though who will play the role is uncertain. Last week, Netflix revealed the first castmembers in its adaptation of The Sandman, the popular DC Comics series written by Neil Gaiman. The announcement made no mention of Constantine, but fans of the series know that the character shows up early on in the series, helping to guide Dream to one of his missing tools. Matt Ryan has built up a dedicated fan following playing John Constantine, first in NBC's Constantine series and then again in the Arrowverse and even voicing the character for DC's animated films. A website misreported that Taron Egerton is playing Constantine in the Sandman show (Egerton lends his voice to Constantine in the Audible audiobook adaptation of The Sandman, which will return with two more installments), angering at least one fan on Twitter. Gaiman responded to this fan, commenting on both Constantine and Gwendoline Christie playing Lucifer over Tom Ellis.
"You can't get from the Lucifer TV series to Sandman #3 or even Season of Mists," Gaiman tweeted. "And we haven't yet announced the casting of Constantine. (That article is just confusing the TV version with the @audible_com version.)"
You can't get from the Lucifer TV series to Sandman #3 or even Season of Mists. And we haven't yet announced the casting of Constantine. (That article is just confusing the TV version with the @audible_com version.) https://t.co/5UwyhnljHa— Neil Gaiman (@neilhimself) January 31, 2021
That doesn't necessarily confirm anything, but Gaiman noting that they haven't announced Constantine's casting seemingly suggests that there is casting to announce. He didn't say anything about Ryan specifically, but he doesn't shoot down the idea either. Feel free to speculate there as you like.
Constantine isn't the only DC Comics character that appears in early issues of The Sandman. Doctor Destiny, Mister Miracle, and the Martian Manhunter appear in the series' first story arc. Gaiman has remained coy about how those characters will or will not be incorporated into the Netflix show, but he has said that he's approaching the show as if he's writing Sandman for the first time in the 21st century and making changes where appropriate.
"[D]oing the Netflix TV series, we're very much looking at that as going, 'Okay, it is 2020, let's say that I was doing Sandman starting in 2020, what would we do? How would we change things? What gender would this character be? Who would this person be? What would be happening?'" Gaiman told ComicBook.com and other press ahead of the Audible adaptation's debut.
Netflix's Sandman cast includes Tom Sturridge as Dream, Gwendoline Christie as Lucifer, Boyd Holbrook as the Corinthian, Vivienne Acheampong as Lucienne, Charles Dance as Roderick Burgess, Asim Chaudhry as Abel, Sanjeev Bhaskar as Cain. The show's first season is currently in production.