We've known since the 2016 San Diego Comic-Con that Brie Larson will play Carol Danvers in the Marvel Cinematic Universe, but it's only been in recent months that the rest of Captain Marvel's cast has started to be assembled. For instance, last month it was reported that Rogue One: A Star Wars Story's Ben Mendelsohn was in talks to join play the main antagonist in the penultimate Phase Three movie. It hasn't been officially confirmed yet if Mendelsohn has signed on yet, but one new report claims that not only is Mendelssohn's involvement a done deal, but he may end up playing Yon-Rogg, a Kree villain.
In addition to heavily featuring the shapeshifting Skrulls, Captain Marvel will also delve into the long war between those shapeshifting aliens and the Kree, the species we've previously seen in Guardians of the Galaxy and Agents of S.H.I.E.L.D. Last week it was reported that Jude Law is being eyed to play Mar-Vell, Carol Danvers' Kree mentor, and now That Hashtag Show states it's heard that Yon-Rogg will also appear in Captain Marvel and could be the role Ben Mendelsohn has been tapped to bring to life. While we can still expect Brie Larson's Carol to battle the Skrulls, it appears that Yon-Rogg is being lined up as the chief antagonist of this story. The Captain Marvel concept art from this year's San Diego Comic-Con showed Carol attacking a Kree officer, so evidently along with dealing with the Skrulls, Carol will also find herself in conflict with at least one Kree operative.
Yon-Rogg, a.k.a. Magnitron, debuted in Marvel Super Heroes #12 as one of Mar-Vell's fellow Kree military officers. Like Mar-Vell, Yon-Rogg was tasked with observing Earth for the Supreme Intelligence to determine if humanity posed a threat. Consumed by his hatred for Mar-Vell, Yon-Rogg tried to kill his nemesis numerous times, and one of his assassination attempts resulted in him targeting Carol Danvers, too. Carol nearly lost her life in that particular incident, but it subsequently led to her gaining superpowers and becoming Ms. Marvel. Outside of the comics, Yon-Rogg has appeared in the Avengers: Earth's Mightiest Heroes animated series and the LEGO Marvel's Avengers video game.
While it's still possible (assuming his deal is finalized) that Ben Mendelsohn could end up playing a Skull leader in Captain Marvel, him portraying Yon-Rogg would also be interesting. Along his presence allowing Captain Marvel to play out more closely to Carol Danvers' comic book origin story, Yon-Rogg's conflict with Mar-Vell sounds more compelling that a general alien invasion story. Sure, the Skrulls would still be presented as formidable threats, but the more personal crux of the movie would revolve around Carol getting caught in Yon-Rogg's quest to eliminate Mar-Vell, whether it stems from jealously or is due to a different reason that's been specifically crafted for the MCU.
Captain Marvel flies into theaters on March 8, 2019. For movies that will be arriving sooner than that, look through our 2018 premiere guide for release date information.