When asked during Justice Con about appearing in future DCEU projects, Lennix suggested a detective movie centered around the Martian Manhunter.
In the comics, the Martian Manhunter is an incredibly long-lived alien who has been stuck on Earth for a long time.
One of the biggest additions to the DCEU with the release of Zack Snyder’s Justice League was the reveal that the character of General Swanwick, played by Harry Lennix, was actually the Martian Manhunter all along.
The one problem is that the J’onn J’onzz lacks any recognizable villains to feature in his solo movie.