Batman and Robin director Joel Shumacher had plans to expand the Dark Knight's world. Though Schumacher never had a "secret script" for another Batman film after Batman and Robin, he did want to make an Arkham Asylum movie -- and he even set up for it at the end of Batman Forever.
"I always wanted to do a whole Arkham movie, and did a scene at the end of Batman Forever when Jim is in a straightjacket and Nicole [Kidman] comes to see him," Schumacher revealed to The Hollywood Reporter. "And it was just a nod to back to Arkham asylum which I love, and I thought it would be fun to put the other villains up there."
However, reports that he also wanted to adapt Frank Miller's Batman: Year One storyline for film are decidedly false. "I remember a few journalists calling me and saying, 'There's a rumor that you felt you never got to make your Batman movie and that you had a secret script. And that you were going to shoot that.' Well, that's all fantasy," he said.
Schumacher certainly would have had plenty of villains to pull from for his Arkham Asylum movie. Between 1989's Batman and 1997's Batman and Robin, many members of the Dark Knight's rogues gallery appeared on screen: the Joker (Jack Nicholson), Catwoman (Michelle Pfeiffer), the Penguin (Danny DeVito), the Riddler (Jim Carrey), Two-Face (Tommy Lee Jones), Mr. Freeze (Arnold Schwarzenegger), Poison Ivy (Uma Thurman), Bane (Jeep Swenson) and more. While some of these villains ultimately perished, comic books and their film adaptations have a habit of bringing the dead back to life for storytelling needs, so it certainly wouldn't have been out-of-line for Schumacher's hypothetical Arkham Asylum film to include them.
However, Schumacher's plans for an Arhkam Asylum spinoff were all for naught. A critical and box office failure, Batman and Robin put an end to the franchise Tim Burton began in 1989.
Justice League, the next film to feature Batman, arrives November 17 and stars Ben Affleck as Batman, Henry Cavill as Superman, Amy Adams as Lois Lane, Gal Gadot as Wonder Woman, Jason Momoa as Aquaman, Ezra Miller as The Flash, Ray Fisher as Cyborg, Willem Dafoe as Vulko, Jesse Eisenberg as Lex Luthor, Jeremy Irons as Alfred Pennyworth, Diane Lane as Martha Kent, Connie Nielsen as Queen Hippolyta and J. K. Simmons as Commissioner Gordon.