The cast of The Suicide Squad continues to grow as Natan Fillion has signed on for a role in the DC Comics adaptation. James Gunn is getting ready to shoot the sequel/reboot in the very near future, which means pre-production is in full swing, and the final pieces of the puzzle are being moved into place. While it's a mystery as to what piece of that puzzle Fillion is going to serve as, the actor is indeed making his way to the DC universe.

According to a new report, Nathan Fillion has boarded the project in a mystery role. Fillion and James Gunn go back a long way. Fillion starred in Gunn's horror/comedy Slither back in 2006, as well as the dark superhero comedy Super as the Holy Avengers. Gunn brought Fillion into the Marvel Cinematic Universe, albeit in a very minor capacity, as Fillion voiced an alien in the Kyln, aka the gigantic space prison in Guardians of the Galaxy. It's unclear if Fillion will have a significant role in The Suicide Squad, or if this will be more in line with a glorified cameo.

Nathan Fillion has been working steadily in Hollywood since the early 2000s. He's best known for his work on shows like Castle, which ran for eight seasons, as well as The Rookie, the cop show he's currently starring on. However, Fillion is arguably still loved most for his role as Captain Malcolm "Mal" Reynolds on Firefly. The sci-fi series ran for just one season, but has maintained a loyal cult following in the years since. Fillion has also starred on Modern Family and A Series of Unfortunate Events in recent years. It's also worth noting that he's voiced Green Lantern in several animated DC projects such as The Death of Superman.

Related: James Gunn Teases Harley Quinn's Return in The Suicide Squad with His King Sharkade

This helps to further fill out an already stacked ensemble that includes familiar faces like Viola Davis (Amanda Waller), Joel Kinnaman (Rick Flag), Jai Courtney (Captain Boomerang) and Margot Robbie (Harley Quinn). New cast members joining the DC universe include David Dastmalchian as Polka Dot Man, Daniela Melchior as Ratcatcher and John Cena as Peacemaker, as well as Idris Elba, who's role remains a mystery. Michael Rooker, another James Gunn regular, was previously said to be playing King Shark. However, we recently learned that Steve Agee will be voicing the character Flula Borg is also on board in a mystery role.

Story details remain under lock and key for the time being, but it was at one point said this will be a total reboot of the franchise. James Gunn has opted not to classify it as a sequel or a reboot. 2016's Suicide Squad, directed by David Ayer, was very successful commercially, but failed to connect critically. We'll be sure to keep you posted as further details on the project are made available. The Suicide Squad is set to hit theaters on August 6, 2021. This news comes to us via Deadline.

Ryan Scott