The Joker terrifies us not because of his violence, but because we cannot predict it.
If brutality were the real power, other slashers would matter equally. Freddy Krueger murders more creatively, Leatherface is more ruthless, Jason Voorhees is more efficient—yet none of them orbit Batman in the collective imagination the way the Joker does.
The actual source of his iconic status emerged in the 1980s and 90s, but not because those stories escalated violence. The Killing Joke and A Death in the Family worked because Joker's violence felt arbitrary and contingent—almost incidental to what made him intelligible.
He wasn't a force of nature pursuing an ideology. He was a man whose motives shifted mid-conversation, whose brutality served no rational endpoint, whose cruelty felt like it could have gone any direction at any moment. You couldn't predict him. Recent Joker comics have flatlined in cultural relevance precisely because the character has been systematized.
The moment you memorize the disturbing moments, the Joker becomes boring.
The moment you memorize the disturbing moments, the Joker becomes boring. You've turned mystery into a ledger. Power doesn't live in the moments you can catalog—it lives in what your audience cannot quite predict about you next. The instant you've explained yourself completely, you've made yourself irrelevant.