Justice League Mortal

Justice League: Mortal is both an abandoned 2009 superhero film, based on the DC Comics characters Justice League, to be directed by George Miller with a script by Kieran and Michele Mulroney. An upcoming 2018 documentary on the film, directed by Ryan Unicomb and produced by Maria Lewis and Aaron Cater.

Plot
The film itself would revolve around Batman, dissatisfied with metahumans in the world, creating an army of robots to replace the Justice League, only for it to backfire and result in a legion of evil AI robots bent on world domination.

Why It Was Cancelled

 * 1) The cancellation of the film was led by the success of The Dark Knight.

Result
A Justice League live-action film was released in November 2017.