The character, Black-Bolt, will make his debut in 2019. Here are five actors that I believe could play him:)
Number Five: Joe Manganiello. I believe Joe has the body- build for Black-Bolt. Though personally, I have not seen him act, I think he could fill the role.
Number Four: The all but forgotten, Luke Hemsworth. Luke, much like his bothers, is also an actor, but hasn't hit it big. Black-Bolt could be his break out role:)
Number Three: The Rock. Now this is highly unlikely, since he has already landed the rule of Shazam, for DC, but The Rock could totally rock this role! He just has the persona! He's big, and he's intimidating:)
Number Two: Tom Hardy. The reason I pick Tom is because this guy can act with his eyes, and since this role has no talking what- so- ever, that just might be important! Not- to- mention the guy is also in great shape, and a good actor:)
Number One: Vin Diesel. This guy has been heavily rumored to play Black-Bolt. He already has ties to the MCU, via Groot, and he is always hinting that he is Black-Bolt! The reason I pick him is because he pretty much fits the character of Black-Bolt perfectly! He's massive, he looks like him LoL, and he is great at playing the intimidating type!