In DC Comics lore, Martian Manhuter is J’onn J’onzz, who is accidentally transported to Earth and becomes a founding member of the Justice League. There have been fan theories about Swanwick as Martian Manhunter since Man of Steel came out in 2013. Fans can only imagine, following the reveal in Justice League, General Swanwick's Martian Manhunter would've been a major presence in the next movie Zack Snyder had planned. Instead, the DCEU is now on a different path. We have a new Batman after Snyder's Ben Affleck, and rumors that Henry Cavill is done as Superman.