Batman Unchained (often mistakenly referred to as Batman Triumphant) was the proposed sequel to Batman & Robin. The film would be the first sequel in the Anthology to connect with the 1989 original film plot, with the return of the Joker.
The film would a return to the darker Batman seen in various degrees in the first three films.
During the filming of Batman & Robin, Warner Bros. was impressed with the dailies. This prompted them to immediately hire Joel Schumacher to return as director for a sequel, but writer Akiva Goldsman, who worked on Batman Forever and Batman & Robin with Schumacher, turned down the chance to write the script. In late 1996, Warner Bros. and Schumacher hired Mark Protosevich to write the script for a fifth Batman film. A projected mid-1999 release date was announced.
Titled Batman Triuphant, Mark Protosevich's script had the Scarecrow as the main villain. The Joker would return as a hallucination in Batman's mind caused by the Scarecrow's fear toxin. Harley Quinn appeared as a supporting character, written as the Joker's daughter trying to get revenge on Batman for the Joker's death in the first film. With Quinn, Mad Hatter appeared also as a supporting character, written with a similar story of Edward Nygma in Batman Forever.
George Clooney, Chris O'Donnell and Alicia Silverstone were set to reprise the roles of Batman, Robin, and Batgirl. Jack Nicholson was set to reprise the role of The Joker from the first film.  Actors Nicolas Cage, Steve Buscemi and Jeff Goldblum were the most likely candidates for the role of Scarecrow.  Singer Madonna was set to portrayed Harley Quinn.
When Batman & Robin was panned by both critics and fans and failed to, make as much money as expected, outgross any of its predecessors, and earn back twice it's budget Warner Bros canceled the project. In 2005, it was released a reboot with no connection with the Anthology.