In addition to his recent reveal that Dick Grayson is dead in the DC Extended Universe, Justice League director Zack Snyder also admitted he'd planned for the new Robin to be Carrie Kelley from Frank Miller and Klaus Janson's The Dark Knight Returns.
A fan on Vero recently asked Snyder if there were plans to bring Dick back after Flashpoint or if he'd stay dead, to which Snyder replied," stay dead...till Carrie."
Debuting in 1940's Detective Comics #38, Dick Grayson was the first character to take the mantle of Robin before eventually branching out from sidekick to full-fledged hero as Nightwing. In the main DC continuity, he was succeeded by Jason Todd, Tim Drake, Stephanie Brown and Damian Wayne.
As for Carrie Kelley, she debuted in the aforementioned Dark Knight Returns, which centered on a 55-year-old Bruce Wayne who decides to leave retirement and fight crime in Gotham once again. Along the way, Wayne meets Kelley, a 13-year-old girl from the streets of Gotham, who would eventually save his life.
Justice League stars Ben Affleck as Batman, Gal Gadot as Wonder Woman, Henry Cavill as Superman, Amy Adams as Lois Lane, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, Jeremy Irons as Alfred Pennyworth, Diane Lane as Martha Kent, Ciarán Hinds as Steppenwolf, Jesse Eisenberg as Lex Luthor and J.K. Simmons as Commissioner Gordon. Zack Snyder's Justice League will premiere exclusively on HBO Max in 2021.