Isabela Merced, Edi Gathegi, and Nathan Fillion join James Gunn's new Superman film.

Nathan Fillion is joining James Gunn's Superman Legacy film as a Green Lantern, with Edi Gathegi and Isabela Merced also announced for the film's cast. They join David Corenswet, who will play the Man of Steel, and Rachel Brosnahan as Lois Lane. Vanity Fair was the first to report the story.

Fillion will play Guy Gardner, a "hulking mass of masculinity" who is also somehow likable despite being, well, obnoxious. Having played a similar role in Dr. Horrible, where he portayed superhero Captain Hammer, Fillion seems like the perfect choice. The character is known for his red bowl haircut, which Vanity Fair confirms will be part of Fillion's look in the new movie.

Fillion is a mainstay of Gunn's films, having previously appeared in Gunn's The Suicide Squad as The Detachable Kid, as well as Slither and Guardians of the Galaxy Vol. 3. Fillion rose to prominence through Firefly, where he played Captain Malcolm Reynolds in both the film and the subsequent movie.

Gathegi, a vetern of the Twilight and X-Men: First Class films, will play Michael Holt, who is known for being a brilliant inventor who first appeared in a 1997 issue of Spectre. Mister Terrific is part of the Justice Society of America and has a rivalry with Batman, which may plant future seeds for the DCU.

As for Merced, she'll be playing Hawkgirl, who first appeared way back in the 1940s. There have been many iterations of Hawkgirl over the years, but all of them are known for using swords, spears, and maces. Merced has previously appeared in Sicario: Day of the Soldado.

source: https://www.ign.com/articles/superman-legacy-casts-nathan-fillion-green-lantern