Gunn, the newly-appointed DC Studios co-CEO with film producer Peter Safran, is in the midst of prepping his reimagined DCU, something that will kick off in 2025 with Superman: Legacy.
In recent weeks fans have begun to learn more about Superman: Legacy with the first hints at its super-powered cast coming in with the announcements of David Corenswet and Rachel Brosnahan as the film's Clark Kent and Lois Lane.
But surely, the movie's two stars were just the start of a much bigger ensemble headed for the DCU epic.
Nathan Fillion Is a Green Lantern
As revealed by Vanity Fair, Nathan Fillion has been cast as a Green Lantern in James Gunn's Superman: Legacy.
The Firefly actor will play the Green Lantern known as Guy Gardner in the film.
While fans may most prominently know Hal Jordan and John Stewart as humans to wear the Green Lantern ring, Garnder is a less heroic version of the hero, likely set to bring a bit of awkward comedy to the James Gunn Superman film.
Fillion has collaborated with Gunn a number of times throughout his career including on DC's The Suicide Squad (in which his character T.D.K. died in the opening minutes) and the recently released Guardians of the Galaxy Vol. 3.
There is currently a Green Lantern Max series on Gunn's new DC slate, titled Lanterns; however, there is no indication that Fillion will reprise his Superman role for that project.
What Fillion's Casting Means for Superman: Legacy
In Nathan Fillion, Superman: Legacy gets someone James Gunn is very familiar with and can keep up with some of the creative antics the filmmaker is known for.
Some may be wondering why Guy Gardner is the first Green Lantern audiences will see after the character has been absent from the big screen for more than 12 years. But he may actually be the perfect version of the hero to reintroduce audiences to the concept of the Lantern Corps.
When Gunn casts most of these character actors, such as Fillion, it is usually in a smaller cameo capacity.
This could mean that Fillion's Guy Gardner could pop up in the film for a few fun comedic bits, teasing the bigger super-powered universe that is out there in this newly-rebooted DCU without taking the focus away from David Corenswet's Man of Steel.
As Gunn has said, this is ultimately "Superman’s journey," and even though another hero or two may be in the movie, everything will come back and run through him.
Plus, with the Lanterns series on the horizon, surely, the filmmaker would not want to give too much away on the Green Lanterns front before then.