9 Movie Deaths You Hear Off-Screen That You Probably Missed The First Time
6. The Joker - Batman: The Killing Joke
This one is admittedly a teensy bit ambiguous, but also a prominent part of the story's lore so absolutely worth mentioning.
Batman: The Killing Joke is an animated adaptation of Alan Moore's 1988 graphic novel of the same name, and similarly ends with Batman capturing The Joker.
The Clown Prince of Crime rejects Bats' offer of rehabilitation and instead tells the Dark Knight a joke about two inmates attempting to escape an insane asylum.
The Joker then laughs to himself and Batman soon joins him, as the camera pans down to the ground and the Joker's laughing stops, all while Batman's ominously continues.
Much like the comic it's left up to viewer interpretation, though the dominant reading is that Batman actually kills the Joker here, hence why he suddenly stops laughing mid-scene.
Fans have pored over both the comic and the film again and again over the years, but in the film at least there's really no other explanation for the Joker's voice just suddenly cutting out mid-laugh.
Presumably, Batman either throttled him or broke his neck, though if you're not familiar with the comic you could easily miss this.