Although Batman has technically died, some of his deaths aren't permanent. It comes with the territory of being a superhero, whether you have actual superpowers or not. Whether you know the name or not, the Electrocutioner went toe to toe with the champ in a bout that led to Batman's short-lived death.
In a tale inside the pages of "Detective Comics #644-646" by Chuck Dixon, Tom Lyle, and Scott Hanna, the Electrocutioner — as his name suggests — electrocuted Batman, resulting in his heart stopping. Though Electrocutioner had temporarily won in a major upset, Robin came prepared by wearing an insulated costume. Robin forced Electrocutioner to reverse the damage. The Electrocutioner then used his electric gloves as a defibrillator to shock Batman back to life. And just like that, Batman was back.
The lesson? Perhaps it's that Robin deserves more credit than what he's given. Or that you don't mess with Batman. Or, maybe most importantly of all, don't underestimate your opponent.