George Clooney's first outing as the Caped Crusader in 1997's Batman and Robin was not supposed to be his last. In fact, Warner Bros. was gearing up to bring back Clooney and co-stars Chris O'Donnell and Alicia Silverstone for a sequel titled Batman Triumphant, which would have been directed by B&R and Batman Forever's Joel Schumacher. However, Batman and Robin was a critical joke, summoning more laughs than its humorous script ever intended to, and audiences who'd flocked to watch Val Kilmer sit behind the Batmobile wheel just two years before simply did not show up to see what Uma Thurman's Poison Ivy and Arnold Schwarzenegger's Mr. Freeze would be adding to the villainous fold this go-round (spoiler: they didn't miss much).
Batman Triumphant was originally given the green light by the studio while Batman and Robin was still mid-production because, somehow, whatever dailies the execs laid eyes on at the time impressed them enough to think a follow up was in short order—until the movie came out. If Batman Triumphant had come to fruition, it would've ushered in the Scarecrow and Harley Quinn (as the Joker's daughter, rather than lover, in this version) as the new do-badders du jour, and they would've been joined by the Joker, Penguin, Catwoman, Two-Face, and The Riddler in an effort to get Bruce Wayne committed to Arkham Asylum.
Clooney, for one, stepped away from superheroism for good after the first film proved to be such a dud and apologized to fans for being any part of it, later admitting, "Let me just say that I'd actually thought I'd destroyed the franchise until somebody else brought it back years later and changed it." That person, of course, Christopher Nolan, who launched his critically acclaimed Dark Knight Trilogy with 2005's Batman Begins—and Christian Bale beneath the cowl.