Batman: Arkham

After the success of Batman & Mr. Freeze: Subzero, Warner Bros. greenlighted the production of a third installment, entitled Batman: Arkham. Boyd Kirkland, the director of this film, was attached to write and direct. The film would have Batman and Robin facing off against a collection of Arkham Asylum escapees, in addition to Batman finding himself falling in love with a new love interest, planned to be voiced by Angie Harmon. The main cast of Batman: The Animated Series was attached to reprise their roles. Steven E. Gordon also drew some art concept for the film. However, the film was cancelled in favor of Batman Beyond: Return of the Joker (which also featured Harmon), while Batman: Arkham eventually became a successful video game series by Rocksteady.

Why It Was Cancelled

 * They were too busy making Batman Beyond: Return of the Joker.