As noted in articles like this one from Spiel Times, online discourse is confident that Henry Cavill has signed a deal to join the Marvel Cinematic Universe. In previous years, speculation suggested that he would portray the MCU's version of Captain Britain (British Captain America ... no, seriously, that's the guy's entire personality). Another rumor circling now is that Cavill has been cast as Hyperion (Marvel's Superman). Still, the most prevailing theory — or possibly just the most prevailing hope — is that he's been cast to play Doctor Doom.
Keep in mind that the D23 Expo confirmed no such thing, but it's easy to understand why a Doctor Doom portrayed by Cavill would entice fans. First, "The Fantastic Four," in which Doctor Doom is a primary villain in the comics, is one of the most hotly anticipated projects coming down the Marvel pipeline. Second, Cavill is beloved for his widely publicized, dutiful nerdiness, poring over source material to inform his characters like Superman and Geralt of Rivia in Netflix's "The Witcher."
Third, and possibly most critical, it's no great stretch to frame his potential entrance into the MCU as a reward for being sidelined by the DCEU. Many fans believe Warner Bros. hasn't treated Cavill's time as Superman with the respect he's due (via Coming Soon). In short, the internet wants Cavill to have another chance at a major superhero franchise, and Doctor Doom would be an epic role worthy of his talents.
