The 29-year-old actor apparently fits the description of Nightwing, Grayson's post-Robin alter-ego. Affleck will play an older and world-weary Batman in the sequel, reported the Wrap.
Two other actors are also in the fray to play Grayson, the Caped Crusader's former sidekick, who's been estranged from Bruce Wayne for years in the movie.
Henry Cavill is set to reprise his role as Superman alongside his 'Man of Steel' co-stars Amy Adams and Laurence Fishburne.
It is also rumoured that the coveted role could be of Wonder Woman or her alter ego Diana Prince.