Batman & Robin (1997)

Batman & Robin (1997) stands as the franchise's worst sequel, nearly destroying the Batman film series with a catastrophic 10% Rotten Tomatoes score. Joel Schumacher's neon-drenched disaster saddled George Clooney with Bat-nipples and Arnold Schwarzenegger's endless ice puns, earning just $238 million worldwide—easily outperformed by #3's $790 million haul. This dramatic plunge from the dark tone of its predecessor ensures it remains the gold standard of sequel catastrophe.