A few Twitter posts previous to the announcement, The Rock happened to post an image of himself wearing a Batman t-shirt.
Let's take a look at five possible characters Dwayne Johnson could be playing in Batman Vs. Superman, Justice League or a related film.
Dwayne Johnson was previously attached to play the Main Man in a live-action film; however, back in March of last year Johnson stated Lobo "came and went." Interestingly enough, around that time speculation began that The Rock might be headed over to Marvel Studios and Disney as the actor mentioned he was interested in the new Star Wars as well as playing Luke Cage. We know Luke Cage is most likely out of the equation as the character will be a part of the Marvel Studios Netflix series, not a big-screen adaptation. Our guess is that with The Rock previously attached to Lobo, there was no way Warner Bros. was letting the popular actor go. With Warner Bros. recently announcing a slate of new DC television shows and movies, and with The Rock mentioning he talked with new WB CEO Kevin Tsujihara, it's possible Lobo is back on the plate. Tsujihara came on board WB after The Rock's comments about Lobo falling apart, so it's definitely possible Lobo could be a contender again. And an anti-hero role would fit Johnson's personality.
2. Martian Manhunter
Jason Momoa is currently rumored for the role of Martian Manhunter in Batman Vs. Superman. It could be possible that Momoa's name was just thrown out there, similar to Drax and the Guardians of the Galaxy movie. We're betting that whatever role Dwayne Johnson will play will be a recurring role with The Rock most likely signing on for a franchise role with numerous movies. Johnson is well-loved by his fans, so a superhero role could definitely be a possibility. The Rock would fit the bill rather nicely as the Martian Manhunter, as the shape-shifting alien is pretty jacked as well.
Does The Rock have to play a hero role? With Wonder Woman added to Batman Vs. Superman, and with Martian Manhunter rumored as well as The Flash, it is looking more and more likely that the Justice League is coming sooner rather than later -- which means Darkseid cometh. While the Justice League movie could easily feature a Superman villain such as Brainiac, Darskeid appears to be the favorite villain of choice. Dwayne Johnson could easily fill the role of a bad guy. He definitely has the size for Darkseid, and with some CGI would look like an ultimate bad arse villain. In addition, Johnson as Darkseid - and the main villain of Justice League - would be a big headline. Johnson could easily appear as Darkseid as a cameo at the end of Batman Vs. Superman.
Fans are waiting for Doomsday to appear on the big screen. The Superman-killer was rumored for Man of Steel. Dwayne Johnson would make a great Doomsday as - again - he has the size. However, we are doubting Dwayne Johnson will be playing the character as essentially anyone can play Doomsday as it's CGI and no speech is required other than a grunt or two. There is also the fact that Doomsday broke Superman's neck, and vice versa, and we just saw Superman do that to Zod in Man of Steel.
With the Justice League on the horizon, maybe just maybe Dwayne Johnson could be playing Cyborg. It seems as if it's a toss up between Cyborg and Martian Manhunter appearing in the movie. Maybe we'll see Dwayne Johnson all teched out as Victor Stone.
Amazo, Despero, Black Adam (seems unlikely with Shazam movie not looking likely); how about Commissioner Gordon?