1988’s “Batman: The Killing Joke,” a seminal graphic novel by Alan Moore and Brian Bolland, has fascinated and horrified fans since its debut. In this gory tale, the Joker breaks out of Arkham Asylum on a mission to prove that “one bad day” is all it takes “to reduce the sanest man alive to lunacy.” The Joker’s supposed backstory is also revealed: He was once a so-so comic transformed by the loss of his pregnant wife and an accident in a chemical plant into a monster (though, as he himself admits, he might be lying about all of this). In the present day, the Joker tortures police chief Jim Gordon and assaults and paralyzes his daughter, Barbara, aka Batgirl. If he subjects Gordon to enough misery, the Joker’s thinking goes, he too will turn to madness. Thankfully, Jim and Babs remain strong despite the ordeal, disproving Joker’s mad theory.
2019’s “Joker” doesn’t directly adapt “The Killing Joke,” but it’s clear that it takes inspiration from the celebrated story. Most prominently, “Joker” features a failed-comic origin story. No less important is the scene in which Arthur and his supposed girlfriend Sophie tell one another they’ve had “a bad day.”